WO2018236183A1 - Semiconductor device - Google Patents

Abstract

Disclosed is a semiconductor device according to an embodiment, comprising: a semiconductor structure comprising a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer arranged between the first conductive semiconductor layer and the second conductive semiconductor layer; a first electrode electrically connected to the first conductive semiconductor layer; and a second electrode electrically connected to the second conductive semiconductor layer, wherein the semiconductor structure comprises a third conductive semiconductor layer arranged between the second conductive semiconductor layer and the second electrode; the third conductive semiconductor layer and the first conductive semiconductor layer comprise an n-type dopant; the second conductive semiconductor layer comprises a p-type dopant; the thickness of the third conductive semiconductor layer is smaller than the thickness of the first conductive semiconductor layer; the dopant concentration of the third conductive semiconductor layer is higher than the dopant concentration of the first conductive semiconductor layer; and the ratio between the aluminum composition of the third conductive semiconductor layer and the aluminum composition of the first conductive semiconductor layer is 1:0.71 to 1:3.5.

Description

Semiconductor device

Embodiments relate to semiconductor devices.

Semiconductor devices including compounds such as GaN and AlGaN have many merits such as wide and easy bandgap energy, and can be used variously as light emitting devices, light receiving devices, and various diodes.

Particularly, a light emitting device such as a light emitting diode or a laser diode using a semiconductor material of Group 3-5 or 2-6 group semiconductors can be applied to various devices such as a red, Blue, and ultraviolet rays. By using fluorescent materials or combining colors, it is possible to realize a white light beam with high efficiency. Also, compared to conventional light sources such as fluorescent lamps and incandescent lamps, low power consumption, , Safety, and environmental friendliness.

In addition, when a light-receiving element such as a photodetector or a solar cell is manufactured using a semiconductor material of Group 3-5 or Group 2-6 compound semiconductor, development of a device material absorbs light of various wavelength regions to generate a photocurrent , It is possible to use light in various wavelength ranges from the gamma ray to the radio wave region. It also has advantages of fast response speed, safety, environmental friendliness and easy control of device materials, so it can be easily used for power control or microwave circuit or communication module.

Accordingly, the semiconductor device can be replaced with a transmission module of an optical communication means, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, White light emitting diodes (LEDs), automotive headlights, traffic lights, and gas and fire sensors. In addition, semiconductor devices can be applied to high frequency application circuits, other power control devices, and communication modules.

In particular, a light emitting device that emits light in the ultraviolet wavelength range can be used for curing, medical use, and sterilization by curing or sterilizing action.

Recently, research on ultraviolet light emitting devices has been actively conducted. However, there is a problem that it is difficult to realize a vertical type ultraviolet light emitting device, and there is a problem that a light output is lowered when a GaN thin film is used for an ohmic characteristic.

The embodiment provides a semiconductor device with improved ohmic characteristics.

Further, a semiconductor device with improved light output is provided.

In addition, a semiconductor device with reduced operating voltage is provided.

Further, a vertical ultraviolet light emitting device is provided.

The problems to be solved in the embodiments are not limited to these, and the objects and effects that can be grasped from the solution means and the embodiments of the problems described below are also included.

A semiconductor device according to an embodiment of the present invention includes a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer Semiconductor structure; A first electrode electrically connected to the first conductive semiconductor layer; And a second electrode electrically connected to the second conductive type semiconductor layer, wherein the semiconductor structure includes a third conductive type semiconductor layer disposed between the second conductive type semiconductor layer and the second electrode, The third conductivity type semiconductor layer and the first conductivity type semiconductor layer may include an n-type dopant, the second conductivity type semiconductor layer may include a p-type dopant, 1 conductivity type semiconductor layer, the dopant concentration of the third conductivity type semiconductor layer is higher than the dopant concentration of the first conductivity type semiconductor layer, and the aluminum composition of the third conductivity type semiconductor layer and the first conductivity type semiconductor layer The ratio of the aluminum composition of the semiconductor layer satisfies 1: 0.71 to 1: 3.5.

The first conductive semiconductor layer, the active layer, the second conductive semiconductor layer, and the third conductive semiconductor layer may include aluminum.

The aluminum composition of the third conductivity type semiconductor layer may be higher than the aluminum composition of the active layer and the first conductivity type semiconductor layer.

The aluminum composition of the third conductivity type semiconductor layer may be lower than the aluminum composition of the active layer and the first conductivity type semiconductor layer.

The second conductivity type semiconductor layer may include a first region where the aluminum composition decreases in the thickness direction, and the third conductivity type semiconductor layer may be disposed between the first region and the second electrode.

The second conductivity type semiconductor layer may include a second region disposed between the first region and the active layer, and the second region may have a constant aluminum composition in the thickness direction.

The change in aluminum composition between the second conductivity type semiconductor layer and the third conductivity type semiconductor layer may be discontinuous.

The aluminum composition of the second conductivity type semiconductor layer and the third conductivity type semiconductor layer may be the same.

The doping concentration of the first conductivity type semiconductor layer is 1 × 10 ¹⁸ / cm ³ to 2 × 10 ²⁰ / cm ³ , and the doping concentration of the third conductivity type semiconductor layer is 2 × 10 ¹⁹ / cm ³ to 3 × 10 ²⁰ / cm < ³ >.

Wherein the semiconductor structure includes the third conductive type semiconductor layer, the second conductive type semiconductor layer, and a plurality of recesses penetrating the active layer to a partial region of the first conductive type semiconductor layer, May be disposed inside the recess, and the second electrode may contact the third conductive type semiconductor layer.

A first conductive layer electrically connected to the first electrode, a second conductive layer electrically connected to the second electrode, a second insulating layer disposed between the first conductive layer and the second conductive layer, 2 < / RTI > conductive layer.

And a bonding layer disposed between the second conductive layer and the conductive substrate.

The active layer can generate light in an ultraviolet wavelength range.

The area ratio of the lower surface of the semiconductor structure to the plurality of recesses may be greater than 1: 0.16 and less than 1: 0.246.

According to the embodiment, the ohmic characteristics can be improved and the operating voltage can be lowered.

Further, light absorption can be suppressed in the semiconductor device, and the light output can be improved.

The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the course of describing a specific embodiment of the present invention.

1 is a conceptual view of a semiconductor structure according to a first embodiment of the present invention,

2 is a graph showing the aluminum composition ratio of the semiconductor structure according to the first embodiment of the present invention,

3 is a graph showing an aluminum composition ratio of a semiconductor structure according to a second embodiment of the present invention,

4 is a graph showing the aluminum composition ratio of the semiconductor structure according to the third embodiment of the present invention,

5 is a graph showing an aluminum composition ratio of a semiconductor structure according to a fourth embodiment of the present invention,

6 is a graph showing the aluminum composition ratio of the semiconductor structure according to the fifth embodiment of the present invention,

7 is a conceptual view of a semiconductor device according to the first embodiment of the present invention,

Fig. 8A is an enlarged view of a portion A in Fig. 7,

FIG. 8B is a partial enlarged view of FIG. 8A,

9A and 9B are diagrams for explaining a configuration in which light output is improved in accordance with the number of recesses,

10 is a plan view of a semiconductor device according to the first embodiment of the present invention,

11 is a plan view of a semiconductor device according to a second embodiment of the present invention,

12 is a plan view of a semiconductor device according to a third embodiment of the present invention,

13 is a plan view of a semiconductor device according to a fourth embodiment of the present invention,

FIG. 14 is a graph showing optical output and power conversion efficiency (Wall-Plug Efficiency) of the semiconductor device according to the first to fourth embodiments,

15 is a conceptual view of a semiconductor device according to a fifth embodiment of the present invention,

Fig. 16 is a plan view of Fig. 15,

17 is a conceptual view of a semiconductor device package according to an embodiment of the present invention,

18 is a plan view of a semiconductor device package according to an embodiment of the present invention,

19 is a modification of Fig.

The embodiments may be modified in other forms or various embodiments may be combined with each other, and the scope of the present invention is not limited to each embodiment described below.

Although not described in the context of another embodiment, unless otherwise described or contradicted by the description in another embodiment, the description in relation to another embodiment may be understood.

For example, if the features of configuration A are described in a particular embodiment, and the features of configuration B are described in another embodiment, even if the embodiment in which configuration A and configuration B are combined is not explicitly described, It is to be understood that they fall within the scope of the present invention.

In the description of the embodiments, in the case where one element is described as being formed "on or under" another element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

FIG. 1 is a conceptual view of a semiconductor structure according to an embodiment of the present invention, and FIG. 2 is a graph illustrating an aluminum composition ratio of a semiconductor structure according to an embodiment of the present invention.

1 and 2, a semiconductor device according to an embodiment includes a first conductive semiconductor layer 124, a second conductive semiconductor layer 127, and a first conductive semiconductor layer 124, Type semiconductor layer 127. The semiconductor structure 120 includes an active layer 126,

The semiconductor structure 120 according to the embodiment of the present invention can output light in the ultraviolet wavelength range. For example, the semiconductor structure 120 may output UV-A at near-ultraviolet wavelength band, UV-B at the far ultraviolet wavelength band, UV-B at deep ultraviolet wavelength band, C can be output. The wavelength range can be determined by the composition ratio of Al of the semiconductor structure 120. [

Illustratively, the near-ultraviolet light (UV-A) may have a peak wavelength in the range of 320 nm to 420 nm, the far ultraviolet light (UV-B) may have a peak wavelength in the range of 280 nm to 320 nm, The light (UV-C) at deep ultraviolet wavelength band may have a peak wavelength in the range of 100 nm to 280 nm.

When the semiconductor structure 120 is for emitting light in the ultraviolet wavelength range, the respective semiconductor layers of the semiconductor structure 120 In _x1 Al _y1 Ga _{1 -x1-} containing aluminum _y1 N (0≤x1≤1, 0 _<y1 1, 0? X1 + y1? 1). Here, the composition of Al can be represented by the ratio of the total atomic weight including the In atomic weight, the Ga atomic weight, and the Al atomic weight to the Al atomic weight. For example, when the Al composition is 40%, the composition of Ga may be Al ₄₀ Ga ₆₀ N of 60%.

Further, in the description of the embodiment, the meaning of the composition is low or high can be understood as a difference (percentage point) of the composition percentage of each semiconductor layer. For example, when the aluminum composition of the first semiconductor layer is 30% and the aluminum composition of the second semiconductor layer is 60%, the aluminum composition of the second semiconductor layer is 30% higher than the aluminum composition of the first semiconductor layer .

The first conductive semiconductor layer 124 may be formed of a compound semiconductor such as Group III-V or Group II-VI, and the first dopant may be doped. The first conductive semiconductor layer 124 may be a semiconductor material having a composition formula of In _x1 Al _y1 Ga _{1 -x1 -y1} N (0? _{X1? 1} , 0 < _{y1? 1} , 0? X1 + y1? For example, AlGaN, AlN, InAlGaN, and the like. The first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. When the first dopant is an n-type dopant, the first conductivity type semiconductor layer 124 doped with the first dopant may be an n-type semiconductor layer.

The first conductivity type semiconductor layer 124 is disposed between the first and second semiconductor layers 124a and 124b and between the first and second semiconductor layers 124a and 124b. And an intermediate layer 124c.

The second sub semiconductor layer 124b may be disposed closer to the active layer 126 than the first sub semiconductor layer 124a. The aluminum composition of the second sub-semiconductor layer 124b may be lower than that of the first sub-semiconductor layer 124a.

The aluminum composition of the second sub semiconductor layer 124b is 40% to 70% when the semiconductor structure 120 emits light UV-C at the deep ultraviolet wavelength band, The composition may be from 50% to 80%. It is possible to improve the light extraction efficiency by lowering the absorption rate of light (UV-C) emitted from the deep ultraviolet wavelength band emitted from the active layer 126 when the aluminum composition of the second sub semiconductor layer 124b is 40% or more, The current injection characteristics into the active layer 126 and the current diffusion characteristics in the second sub semiconductor layer 124b can be ensured.

Further, when the aluminum composition of the first sub-semiconductor layer 124a is 50% or more, the absorption efficiency of light (UV-C) emitted from the deep ultraviolet wavelength band emitted from the active layer 126 can be lowered, The current injection characteristics into the active layer 126 and the current diffusion characteristics in the first sub semiconductor layer 124a can be ensured.

When the aluminum composition of the first sub semiconductor layer 124a is higher than the aluminum composition of the second sub semiconductor layer 124b, light is extracted from the active layer 126 to the outside of the semiconductor structure 120 due to the difference in refractive index The light extraction efficiency of the semiconductor structure 120 can be improved.

The thickness of the second sub-semiconductor layer 124b may be thinner than the thickness of the first sub-semiconductor layer 124a. The first sub-semiconductor layer 124a may be 130% or more of the thickness of the second sub-semiconductor layer 124b. According to this structure, since the intermediate layer 124c is disposed after the thickness of the first sub semiconductor layer 124a having a high aluminum composition is sufficiently secured, the crystallinity of the entire semiconductor structure 120 can be improved.

The aluminum composition of the intermediate layer 124c may be lower than the aluminum composition of the first conductivity type semiconductor layer 124 and the second conductivity type semiconductor layer 124. The intermediate layer 124c may be a region in contact with the first electrode. In addition, the intermediate layer 124c may serve to absorb the laser beam irradiated to the semiconductor structure 120 during the LLO (Laser Lift-off) process for removing the growth substrate, thereby preventing the active layer 126 from being damaged. Accordingly, the semiconductor device according to the embodiment can prevent the active layer 126 from being damaged during the LLO (Laser Lift-off) process, and thus the optical output and electrical characteristics can be improved.

The thickness of the intermediate layer 124c and the aluminum composition can be appropriately adjusted to absorb the laser irradiated to the semiconductor structure 120 during the LLO process. Therefore, the aluminum composition of the intermediate layer 124c may correspond to the wavelength of the laser light used in the LLO process, and the aluminum composition of the intermediate layer 124c may be 30% to 60% when the laser for the LLO is 200 nm to 300 nm, Lt; / RTI &gt;

Illustratively, when the wavelength of the LLO laser is lower than 270 nm, the aluminum composition of the intermediate layer 124c may be increased to 50% to 70%. If the aluminum composition of the intermediate layer 124c is higher than the aluminum composition of the well layer 126a, the intermediate layer 124c may not absorb light emitted from the active layer 126. [ Therefore, the light extraction efficiency can be improved.

The intermediate layer 124c has a first intermediate layer (not shown) having a lower aluminum composition than the first conductivity type semiconductor layer 124 and a second intermediate layer (not shown) having a higher aluminum composition than the first conductivity type semiconductor layer 124 . A plurality of the first intermediate layer and the second intermediate layer may be alternately arranged.

The active layer 126 may be disposed between the first semiconductor layer and the second semiconductor layer. The first semiconductor layer may be a first conductive semiconductor layer 124 and the second semiconductor layer may include a second conductive semiconductor layer 127 and an electron blocking layer 129.

The active layer 126 is a layer where electrons (or holes) injected through the first conductive type semiconductor layer 124 and holes (or electrons) injected through the second conductive type semiconductor layer 127 meet. The active layer 126 transitions to a low energy level as electrons and holes recombine, and can generate light having ultraviolet wavelengths.

The active layer 126 may have any one of a single well structure, a multiple well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, Is not limited thereto.

The active layer 126 may include a plurality of well layers 126a and a barrier layer 126b. The well layer 126a and the barrier layer 126b may have a composition formula of In _{x 2} Al _{y 2} Ga _{1 -x 2 -y 2} N (0? X _{2 ? 1} , 0 < _{y 2 ? 1} , 0? X 2 + y 2? 1) . The composition of the aluminum layer in the well layer 126a may vary depending on the wavelength of light emitted.

The second conductive semiconductor layer 127 may be disposed on the active layer 126 and may be formed of a compound semiconductor such as a group III-V or II-VI group. In the second conductive semiconductor layer 127, The dopant can be doped. A second conductive semiconductor layer 127 is a semiconductor material having a compositional formula of _{In x5 Al y2 Ga 1 -x5- y2} N (0≤x5≤1, 0 <y2≤1, 0≤x5 + y2≤1) or AlGaN , AlInN, AlN, AlGaAs, AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, or Ba, the second conductivity type semiconductor layer 127 doped with the second dopant may be a p-type semiconductor layer.

The third conductive semiconductor layer 128 may be disposed on the second conductive semiconductor layer 127. The third conductive semiconductor layer 128 may be disposed on the surface region So of the semiconductor structure 120 in contact with the second electrode. The resistance between the third conductivity type semiconductor layer 128 and the second electrode may be one or more of an ohmic contact, a Schottky contact, or a tunneling effect, but the present invention is not limited thereto. A current may be injected into the third conductive type semiconductor layer 128 through the second electrode and a current injection efficiency may be controlled by a resistance between the third conductive type semiconductor layer 128 and the second electrode .

The third conductive semiconductor layer 128 may be formed of a compound semiconductor such as a III-V group or a II-VI group, and the first dopant may be doped. The first conductive semiconductor layer 124 may be a semiconductor material having a composition formula of In _x1 Al _y1 Ga _{1 -x1 -y1} N (0? _{X1? 1} , 0 < _{y1? 1} , 0? X1 + y1? For example, AlGaN, InAlGaN, AlN, and the like. The first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. That is, the third conductive semiconductor layer 128 may be the same n-type semiconductor layer as the first conductive semiconductor layer 124.

The electron blocking layer 129 may be disposed between the active layer 126 and the second conductive semiconductor layer 127. The electron blocking layer 129 blocks the flow of the carriers supplied from the first conductivity type semiconductor layer 124 to the second conductivity type semiconductor layer 127 and causes electrons and holes to recombine within the active layer 126 The probability can be increased. The energy band gap of the electron blocking layer 129 may be greater than the energy band gap of the active layer 126 and / or the second conductivity type semiconductor layer 127. The electron blocking layer 129 may be defined as a part of the second conductive type semiconductor layer 127 because the second dopant is doped.

The electron blocking layer 129 is a semiconductor material having a composition formula of In _{x 1} Al _{y 1} Ga _{1 -x 1 -y 1} N (0? _{X 1 ? 1} , 0? _{Y 1 ? 1} , 0? _{X 1 + y 1 ? 1} ) , AlN, InAlGaN, and the like, but is not limited thereto.

The first conductivity type semiconductor layer 124, the active layer 126, the second conductivity type semiconductor layer 127, and the electron blocking layer 129 may all comprise aluminum. Therefore, the first conductivity type semiconductor layer 124, the active layer 126, the second conductivity type semiconductor layer 127, and the electron blocking layer 129 may have an AlGaN, InAlGaN, or AlN composition.

The electron blocking layer 129 may have an aluminum composition of 50% to 100%. If the aluminum composition of the electron blocking layer 129 is less than 50%, it may have a sufficient energy barrier for blocking electrons and may not absorb the light emitted from the active layer 126.

The electron blocking layer 129 may include a first section 129a and a second section 129b. The first section 129a may have a higher aluminum composition in the direction from the first conductivity type semiconductor layer 124 to the second conductivity type semiconductor layer 127. [ The aluminum composition of the first section 129a may be 80% to 100%. Accordingly, the first section 129a of the electron blocking layer 129 may be a portion having the highest Al composition in the semiconductor structure 120. [ The first section 129a may be AlGaN or AlN. Or the first section 129a may be a superlattice layer in which AlGaN and AlN are alternately arranged.

The thickness of the first section 129a may be about 0.1 nm to 4 nm. In order to effectively block the movement of the electrons, the thickness of the first section 129a can be set to 0.1 nm or more. In order to secure injection efficiency of holes from the second conductivity type semiconductor layer 127 to the active layer 126, the thickness of the first section 129a may be 4 nm or less.

The efficiency of hole injection from the second conductivity type semiconductor layer 127 to the active layer 126 and the efficiency of electron transfer from the first conductivity type semiconductor layer 124 to the second conductivity type semiconductor layer 127 In order to secure the blocking efficiency, the thickness of the first section 129-a is set to 0.1 nm or more and 4 nm or less. However, when it is necessary to selectively secure any one of the electron blocking function and the hole injection function, It may be out of range.

The third section 129c disposed between the first section 129a and the second section 129b may include an undoped section that does not include a dopant. Therefore, the third section 129c can prevent the dopant from diffusing from the second conductivity type semiconductor layer 127 to the active layer 126. [

The second conductivity type semiconductor layer 127 may include a third sub-semiconductor layer 127a and a fourth sub-semiconductor layer 127b.

The thickness of the third sub-semiconductor layer 127a may be greater than 10 nm and less than 50 nm. Illustratively, the thickness of the third sub-semiconductor layer 127a may be 25 nm. When the thickness of the third sub-semiconductor layer 127a is larger than 10 nm, the resistance decreases in the horizontal direction and the current diffusion efficiency can be improved. When the thickness of the third sub semiconductor layer 127a is smaller than 50 nm, the path through which the light incident on the third sub semiconductor layer 127a from the active layer 126 is absorbed can be shortened, The efficiency can be improved.

The aluminum composition of the third sub semiconductor layer 127a may be higher than the aluminum composition of the well layer 126a. The aluminum composition of the well layer 126a for producing deep ultraviolet or far ultraviolet light may be about 20% to 60%. Therefore, the aluminum composition of the third sub semiconductor layer 127a may be greater than 40% and less than 80%. Illustratively, if the aluminum composition of the well layer 126a is 30%, the aluminum composition of the third sub-semiconductor layer 127a may be 40%.

If the aluminum composition of the third sub semiconductor layer 127a is lower than the aluminum composition of the well layer 126a, the probability that the third sub semiconductor layer 127a absorbs ultraviolet light is very high, have.

The fourth sub semiconductor layer 127b may have a relatively uniform aluminum composition to improve hole injection efficiency or improve crystallinity of the semiconductor structure. The thickness of the fourth sub-semiconductor layer 127b may be 20 nm to 60 nm. The aluminum composition of the fourth sub-semiconductor layer 127b may be 40% to 80%.

The third conductive semiconductor layer 128 may be a surface layer (So) of the semiconductor structure in contact with the second electrode. The third conductive semiconductor layer 128 may have a high doping concentration and a small thickness. Therefore, the ohmic resistance of the third conductivity type semiconductor layer 128 with respect to the second electrode 146 may be lowered due to the tunneling effect.

The third conductive semiconductor layer 128 may be doped with an n-type dopant. Accordingly, the third conductivity type semiconductor layer 128 and the first conductivity type semiconductor layer 124 may all be n-AlGaN. However, the doping concentration, the aluminum composition, and the thickness of the third conductivity type semiconductor layer 128 and the first conductivity type semiconductor layer 124 may be different.

The doping concentration of the third conductivity type semiconductor layer 128 may be higher than the doping concentration of the first conductivity type semiconductor layer 124 to have a turling effect. Illustratively, the doping concentration of the first conductivity type semiconductor layer 124 is 1 × 10 ¹⁸ / cm ³ to 2 × 10 ²⁰ / cm ³ , and the doping concentration of the third conductivity type semiconductor layer 128 is 2 × 10 ¹⁹ / cm ³ to ³ × 10 ²⁰ / cm 3 may be.

The thickness of the third conductivity type semiconductor layer 128 may be 1 nm to 10 nm, or 1 nm to 5 nm. When the thickness of the third conductivity type semiconductor layer 128 is larger than 10 nm, there is a problem that the injection efficiency of holes becomes weak. Therefore, the thickness of the third conductivity type semiconductor layer 128 may be smaller than that of the first conductivity type semiconductor layer 124 and the second conductivity type semiconductor layer 127.

The thickness of the third conductivity type semiconductor layer 128 may be smaller than the thickness of the third sub semiconductor layer 127a. The thickness ratio of the third sub semiconductor layer 127a and the third conductivity type semiconductor layer 128 may be 1.5: 1 to 20: 1. If the thickness ratio is smaller than 1.5: 1, the thickness of the third sub semiconductor layer 127a becomes too thin, and the current injection efficiency can be reduced. In addition, when the thickness ratio is larger than 20: 1, the thickness of the third conductivity type semiconductor layer 128 becomes too thin, and the ohmic reliability may be deteriorated.

Since the injection efficiency of holes is improved by the tunneling effect of the third conductive type semiconductor layer 128, the aluminum composition may be controlled to be relatively higher than that of the well layer 126a. The third conductivity type semiconductor layer 128 may have an aluminum composition of 1% to 80%.

Table 1 below is a table in which the second electrode is connected to a surface layer containing aluminum to measure the operation voltage and luminous intensity of the light emitting device.

In the first experiment, the aluminum composition of the second conductivity type semiconductor layer 127 was lowered to 5% to form a surface layer, and the second electrode was connected to the second electrode.

In the second experimental example, the third conductivity type semiconductor layer 128 of n-AlGaN (Al: 25%) was formed on the second conductivity type semiconductor layer 127 and the second electrode was connected.

In the third experimental example, the third conductivity type semiconductor layer 128 of n-AlGaN (Al: 40%) was formed on the second conductivity type semiconductor layer 127 and the second electrode was connected.

The light emitting devices of the first through third experimental examples were fabricated in the same manner except for the ohmic structure, and 350 mA current was applied to each light emitting device.

	Operating voltage (V)	Brightness (mW)
Example 1	7.10	80.1
Example 2	6.16	85.2
Example 3	6.40	84.5

Referring to Table 1, when the aluminum composition of the second conductivity type semiconductor layer 127 is lowered and the second electrode is electrically connected to the second electrode, an operation voltage of 7.10 V and a luminous intensity of 80.1 mW are measured as in the first experimental example. When the GaN thin film is formed on the second conductivity type semiconductor layer 127 to improve the ohmic characteristics, the operating voltage can be lowered. However, the GaN thin film absorbs most of the ultraviolet light and the light output may be weak.

However, when the third conductive semiconductor layer 128 of n-AlGaN is formed and electrically connected to the second electrode as in the second experimental example, the operating voltage is low even though the aluminum composition is increased from 5% to 25% . This is because the hole injection efficiency is improved by the tunneling effect or the improvement of the ohmic characteristic. Further, since the aluminum composition is high, the problem that the third conductivity type semiconductor layer 128 absorbs ultraviolet light can be also improved.

According to the embodiment, by disposing the third conductive type semiconductor layer 128 between the second conductive type semiconductor layer 127 and the second electrode, the operating voltage can be lowered and the light output can be improved.

Referring to the third experimental example, it can be seen that when the composition of the aluminum of the third conductivity type semiconductor layer 128 is increased to 40%, the operating voltage rises to about 0.34V. However, it can be seen that the operating voltage is lower than that of the first experimental example.

According to the embodiment, the aluminum composition of the third conductive type semiconductor layer 128 may be 20% to 70%. When the composition of aluminum is 20% or more, the difference in aluminum composition with the well layer 126a is reduced, and the light absorption can be improved. In addition, when the composition of aluminum is 70% or less, the operating voltage is excessively increased and the decrease of the light output can be improved.

The average aluminum composition of the first conductivity type semiconductor layer 124 may be larger than that of the active layer. The average aluminum composition of the first conductivity type semiconductor layer 124 may be 50% to 70%.

Therefore, the ratio of the aluminum composition of the third conductivity type semiconductor layer 128 to the aluminum composition of the first conductivity type semiconductor layer 124 may be 1: 0.71 to 1: 3.5.

When the composition ratio is 1: 0.71 or more (for example, 1: 0.8), the aluminum composition of the first conductivity type semiconductor layer 124 increases and crystallinity can be improved. Further, the probability of absorbing the light emitted from the well layer is reduced, and the light output can be improved.

When the composition ratio is 1: 3.5 or less, the probability that the third conductivity type semiconductor layer 128 absorbs light emitted from the well layer can be reduced while maintaining an appropriate operating voltage. Therefore, the light output can be lowered.

The second conductivity type semiconductor layer 127 has a uniform aluminum composition in the fourth sub semiconductor layer 127b in the direction away from the active layer 126 and gradually increases in the aluminum composition in the third sub semiconductor layer 127a Can be reduced. In addition, the aluminum composition in the thickness direction of the third conductivity type semiconductor layer 129 may also decrease. The reduction width of the aluminum composition of the third sub semiconductor layer 127a may be different from or the same as the reduction width of the third conductivity type semiconductor layer 128. [ However, the present invention is not limited thereto, and the aluminum composition of the third conductive type semiconductor layer 128 may be constant.

According to the embodiment, the aluminum composition (P3) of the third conductivity type semiconductor layer may be lower than the aluminum composition (P1) of the well layer and the aluminum composition (P4) of the intermediate layer. In this case, the ohmic resistance with the second electrode can be effectively lowered. However, the present invention is not limited thereto, and the aluminum composition of the third conductivity type semiconductor layer may be variously modified as described later.

FIG. 3 is a graph showing the aluminum composition ratio of the semiconductor structure according to the second embodiment of the present invention. FIG. 4 is a graph showing the aluminum composition ratio of the semiconductor structure according to the third embodiment of the present invention. 5 is a graph showing the aluminum composition ratio of the semiconductor structure according to the fourth embodiment.

Referring to FIG. 3, the aluminum composition P3 of the third conductive semiconductor layer 128 may be higher than the aluminum composition P1 of the well layer 126a and lower than the aluminum composition P4 of the intermediate layer 124c. The aluminum composition of the well layer 126a can be controlled according to the wavelength of the generated light. Illustratively, the aluminum composition may be between 20% and 30% to produce the UVB wavelength, and the aluminum composition may be between 30% and 50% to produce the UVC wavelength. At this time, if the aluminum composition P3 of the third conductive type semiconductor layer 128 is controlled to be higher than the aluminum composition P1 of the well layer 126a, the light absorption of the third conductive type semiconductor layer 128 may be improved .

The aluminum composition of the intermediate layer 124c may be 50% to 70%. Therefore, when the aluminum composition P3 of the third conductivity type semiconductor layer 128 is set lower than the aluminum composition P4 of the intermediate layer 124c, it is possible to prevent an excessive increase in the operating voltage.

According to the embodiment, the hole injection efficiency can be improved even if the composition of aluminum is increased by the tunneling effect. Therefore, the light absorption rate can be improved by controlling the aluminum composition P3 of the third conductivity type semiconductor layer 128 to be higher than the aluminum composition P1 of the well layer 126a.

From the viewpoint of the ohmic characteristic, it is advantageous that the lower the aluminum composition of the third conductivity type semiconductor layer 128 is, and the higher the aluminum composition from the viewpoint of light absorption. Therefore, the aluminum composition P3 of the third conductivity type semiconductor layer can be controlled to be higher than the aluminum composition P1 of the well layer and lower than the aluminum composition of the second conductivity type semiconductor layer 127 or the intermediate layer 124c. At this time, the third sub semiconductor layer 127a may have a slope so that the aluminum composition continuously changes.

Referring to FIG. 4, the aluminum composition P3 of the third conductivity type semiconductor layer 128 and the aluminum composition change of the second conductivity type semiconductor layer 127 may be discontinuous. The third conductive type semiconductor layer 128 can be formed without reducing the composition of the aluminum if the difference in the aluminum composition P3 between the second conductive type semiconductor layer 127 and the third conductive type semiconductor layer is not large.

5, the second conductivity type semiconductor layer 127 and the third conductivity type semiconductor layer 128 may have the same aluminum composition. As described above, the hole injection efficiency of the third conductive type semiconductor layer 128 can be improved by the tunneling effect even if the aluminum composition is high. Therefore, it may be advantageous to control the aluminum composition of the second conductivity type semiconductor layer 127 and the third conductivity type semiconductor layer 128 in the light extraction viewpoint.

In this case, the doping concentration of the dopant is maximized and the thickness of the third conductivity type semiconductor layer 128 is minimized in order to obtain an appropriate ohmic resistance.

6 is a graph showing the aluminum composition ratio of the semiconductor structure according to the fifth embodiment of the present invention.

The second conductive semiconductor layer 127 of the semiconductor device according to the embodiment is the same as the configuration of FIG. 2 except that the surface layer 127a in contact with the second electrode is P-AlGaN containing P-type dopant . When the GaN thin film is disposed between the second conductive type semiconductor layer 127 and the second electrode 246 for ohmic contact, the GaN thin film absorbs most of the light with the ultraviolet wavelength, and thus the optical characteristic is deteriorated. Therefore, in the embodiment, it is necessary to adjust the aluminum composition of the second conductivity type semiconductor layer 127 so that ohmic contact with the second electrode is possible without using the GaN thin film.

The second conductivity type semiconductor layer 127 may include a second-first semiconductor layer 127-1 and a second-second semiconductor layer 127-2. The second-first semiconductor layer 127-1 may be a surface region So in direct contact with the second electrode 146. [ The second-second semiconductor layer 127-2 may be disposed between the electron blocking layer 129 and the second-1 semiconductor layer 127-1.

The aluminum composition of the second-first semiconductor layer 127-1 may be lower than the aluminum composition of the well layer 126a. Here, the well layer 126a may be a well layer having the lowest Al composition among a plurality of well layers. If the aluminum composition of the second-first semiconductor layer 127-1 is higher than the aluminum composition of the well layer 126a, the resistance between the second-first semiconductor layer 127-1 and the second electrode 146 becomes high There is a problem that sufficient ohmic is not achieved and the current injection efficiency is low.

The average aluminum composition of the second-first semiconductor layer 127-1 may be 1% to 35%, or 1% to 10%. If it is larger than 35%, the second electrode may not be sufficiently amorphous. If the composition is less than 1%, the GaN composition is close to the GaN composition, and light is absorbed.

The thickness of the (2-1) th semiconductor layer 127-1 may be 1 nm to 10 nm. As described above, since the composition of aluminum is low for the ohmic operation, the second-first semiconductor layer 127-1 can absorb ultraviolet light. Therefore, it is advantageous from the viewpoint of light output to control the thickness of the (2-1) th semiconductor layer 127-1 as thin as possible.

However, when the thickness of the (2-1) th semiconductor layer 127-1 is controlled to 1 nm or less, it is difficult to lower the aluminum composition considerably because it is too thin. In addition, when the thickness is thicker than 10 nm, the amount of light absorbed becomes too large, and the light output efficiency may decrease.

The thickness of the second-second semiconductor layer 127-2 may be larger than 10 nm and smaller than 100 nm. Illustratively, the thickness of the second-second semiconductor layer 127-2 may be 25 nm. If the thickness of the second-second semiconductor layer 127-2 is less than 10 nm, the resistance increases in the horizontal direction, and the current injection efficiency may be lowered. In addition, when the thickness of the second-second semiconductor layer 127-2 is larger than 100 nm, the resistance increases in the vertical direction and the current injection efficiency may be lowered.

The thickness of the second-first semiconductor layer 127-1 may be smaller than the thickness of the second-second semiconductor layer 127-2. The thickness ratio of the second-first semiconductor layer 127-1 and the second-second semiconductor layer 127-2 may be 1: 5 to 1:50. If the thickness ratio is smaller than 1: 5, the thickness of the (2-1) th semiconductor layer 127-1 becomes too thick, and the light output efficiency may be lowered. In addition, when the thickness ratio is larger than 1:50, the thickness of the second-first semiconductor layer 127-1 may become too thin. Therefore, it may be difficult to lower the aluminum composition to a desired aluminum composition within a thin thickness range. Therefore, ohmic reliability may be degraded.

The aluminum composition of the second-second semiconductor layer 127-2 may be higher than that of the well layer 126a. Illustratively, the aluminum composition of the well layer 126a may be about 30% to 50% to produce ultraviolet light. If the aluminum composition of the second-second semiconductor layer 127-2 is lower than the aluminum composition of the well layer 126a, the second-second semiconductor layer 127-2 absorbs light, .

The average aluminum composition of the second-second semiconductor layer 127-2 may be greater than 40% and less than 80%. When the aluminum composition of the second-second semiconductor layer 127-2 is less than 40%, there is a problem of absorbing light. When the aluminum composition is more than 80%, the current injection efficiency is deteriorated. Illustratively, the average aluminum composition of the second-second semiconductor layer 127-2 may be 50%.

The second-second semiconductor layer 127-2 may become smaller as the aluminum composition is further away from the active layer 126 in the section 127-4. At this time, the aluminum reduction width of the second-first semiconductor layer 127-1 may be larger than the aluminum reduction width of the section 127-4 of the second-second semiconductor layer 127-2. That is, the Al compositional change rate of the second-first semiconductor layer 127-1 in the thickness direction may be larger than the Al composition change rate of the second-second semiconductor layer 127-2.

The thickness of the second-second semiconductor layer 127-2 is thicker than that of the second-first semiconductor layer 127-1, while the aluminum composition must be higher than that of the well layer 126a. However, since the second-first semiconductor layer 127-1 has a small thickness and a large variation range of the aluminum composition, the decrease in the aluminum composition may be relatively large.

The lowest point of aluminum in the second conductivity type semiconductor layer 127 may be the point where the second-1 semiconductor layer 127-1 contacts the second electrode. At this time, the aluminum composition may be 1% to 10%. When the aluminum composition is less than 1%, the light absorption amount may be high, and when the aluminum composition is more than 10%, the ohmic characteristic may be deteriorated.

The point where aluminum is highest in the second conductivity type semiconductor layer 127 may be the closest point to the electron blocking layer 129. At this time, as described above, the aluminum composition of the electron blocking layer 129 may be 50% to 90%. Therefore, the aluminum maximum composition of the second conductivity type semiconductor layer 127 may be 50% to 90%.

Therefore, the aluminum composition change in the thickness direction of the second conductivity type semiconductor layer 127 may be 1% to 90%, or 10% to 90%. In addition, the lowest aluminum composition and the highest aluminum composition ratio of the second conductivity type semiconductor layer 127 may be 1: 5 to 1: 90.

FIG. 7 is a conceptual diagram of a semiconductor device according to the first embodiment of the present invention, wherein FIG. 8A is an enlarged view of a portion A in FIG. 7, and FIG. 8B is a partially enlarged view of FIG. 8A.

7, a semiconductor device according to an embodiment includes a semiconductor structure 120 including a first conductivity type semiconductor layer 124, a second conductivity type semiconductor layer 127, and an active layer 126, And a second electrode 146 electrically connected to the second conductivity type semiconductor layer 127. The first electrode 142 is electrically connected to the first conductivity type semiconductor layer 124 and the second electrode 146 is electrically connected to the second conductivity type semiconductor layer 127. [

The first conductive semiconductor layer 124, the active layer 126, and the second conductive semiconductor layer 127 may be disposed in a first direction (Y direction). Hereinafter, a first direction (Y direction), which is the thickness direction of each layer, is defined as a vertical direction, and a second direction (X direction) perpendicular to the first direction (Y direction) is defined as a horizontal direction. The structure of the semiconductor structure may include all of the structures described in Figs. 1 to 6.

The semiconductor structure 120 may include a plurality of recesses 128 disposed through a portion of the first conductivity type semiconductor layer 124 through the second conductivity type semiconductor layer 127 and the active layer 126 .

The first electrode 142 may be disposed on the upper surface of the recess 128 and may be electrically connected to the first conductive semiconductor layer 124. The second electrode 146 may be disposed under the second conductive semiconductor layer 127.

The first electrode 142 and the second electrode 146 may be ohmic electrodes. The first electrode 142 and the second electrode 146 may be formed of one selected from the group consisting of ITO (indium tin oxide), IZO (indium zinc oxide), IZTO (indium zinc tin oxide), IAZO (indium aluminum zinc oxide), IGZO ), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO ZnO, ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au or Ni / IrOx / Au / ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ru, Mg, Zn, Pt, Au, and Hf. However, the present invention is not limited to these materials. Illustratively, the first electrode may have a plurality of metal layers (e.g. Cr / Al / Ni) and the second electrode may be ITO.

8A and 8B, as the Al composition of the semiconductor structure 120 increases, current diffusion characteristics within the semiconductor structure 120 may be degraded. In addition, the amount of light emitted in the lateral direction of the semiconductor device increases in the active layer 126 (TM mode) as compared with the GaN-based blue light emitting device. This TM mode can mainly occur in an ultraviolet semiconductor device.

In the ultraviolet light emitting device, the current diffusion characteristics may be degraded in the semiconductor structure, and a uniform current density characteristic in the semiconductor structure is secured, so that a smooth current injection is required to secure the electrical and optical characteristics and reliability of the semiconductor device. Accordingly, a relatively large number of recesses 128 can be formed in order to inject the current into the first electrode 142 in comparison with a conventional GaN-based semiconductor structure. Hereinafter, components for improving current diffusion characteristics and current injection characteristics that are degraded when a GaN-based semiconductor structure includes Al will be described.

The first insulating layer 131 may electrically isolate the first electrode 142 from the active layer 126 and the second conductive type semiconductor layer 127. The first insulating layer 131 may electrically isolate the second electrode 146 and the second conductive layer 150 from the first conductive layer 165. The first insulating layer 131 may function to prevent the side surface of the active layer 126 from being oxidized during the process of the semiconductor device.

The first insulating layer 131 is SiO _2, SixOy, Si ₃ N _4, SixNy, SiOxNy, Al ₂ O _3, TiO _2, but may be at least one is selected and formed from the group consisting of AlN, etc., is not limited to, . The first insulating layer 131 may be formed as a single layer or a multilayer. Illustratively, the first insulating layer 131 may be a DBR (distributed Bragg reflector) having a multi-layer structure including silver oxide or Ti compound. However, the first insulating layer 131 may include various reflective structures without being limited thereto.

When the first insulating layer 131 performs a reflection function, the light extracting efficiency can be improved by upwardly reflecting the light L1 emitted toward the side surface of the active layer 126. [ In this case, as the number of recesses 128 increases, the light extraction efficiency may be more effective.

The diameter W3 of the first electrode 142 may be 24 占 퐉 or more and 50 占 퐉 or less. When this range is satisfied, it is advantageous for current dispersion and a large number of first electrodes 142 can be disposed. The current injected into the first conductivity type semiconductor layer 124 can be sufficiently secured when the diameter W3 of the first electrode 142 is greater than 24 mu m and when the diameter W3 is 50 mu m or less, The number of the first electrodes 142 disposed in the area of the first electrode 124 can be sufficiently secured and the current dispersion characteristics can be ensured.

The diameter W1 of the recess 128 may be 38 탆 or more and 60 탆 or less. The diameter W1 of the recess 128 may be defined as the widest area in the recess disposed below the second conductive type semiconductor layer 127. [ The diameter W1 of the recess 128 may be the diameter of the recess 128 disposed on the bottom surface of the second conductive type semiconductor layer 127. [

When forming the first electrode 142 disposed inside the recess 128 when the diameter W1 of the recess 128 is 38 占 퐉 or more, the first electrode 142 is a first conductive type It is possible to secure a process margin for securing an area for electrically connecting to the semiconductor layer 124 and to prevent the volume of the active layer 124 decreasing for disposing the first electrode 142 And therefore the luminous efficiency can be deteriorated.

The inclination angle [theta] 5 of the recess 128 may be 70 degrees to 90 degrees. If such an area range is satisfied, it may be advantageous to form the first electrode 142 on the upper surface, and a large number of recesses 128 may be formed.

If the inclination angle [theta] 5 is less than 70 degrees, the area of the active layer 124 to be removed can be increased, but the area in which the first electrode 142 is disposed can be reduced. Therefore, the current injection characteristic may be lowered, and the luminous efficiency may be lowered. Therefore, the area ratio between the first electrode 142 and the second electrode 146 can be adjusted by using the inclination angle [theta] 5 of the recess 128.

The thickness d2 of the first electrode 142 may be smaller than the thickness d3 of the first insulating layer 131 and the distance d4 between the first insulating layer 131 and the first electrode 142 may be 0 占 퐉 to 4 占 퐉. .

When the thickness d2 of the first electrode 142 is thinner than the thickness d3 of the first insulating layer 131, the peeling and cracks And the like can be solved. In addition, the gap-fill characteristic of the second insulating layer 132 can be improved by providing the first insulating layer 131 and the spacing d4.

The distance d4 between the first electrode 142 and the first insulating layer 131 may be 0 탆 or more and 4 탆 or less. The width of the first insulating layer 131 disposed on the upper surface of the recess 128 can be secured when the distance d4 between the first electrode 142 and the first insulating layer 131 is less than 4 mu m, The obtained width of the first insulating layer 131 can provide the function of the current blocking layer, thereby ensuring the reliability of the semiconductor device.

The upper surface 143 of the recess 128 is electrically connected to the first region d5 where the first insulating layer 131 and the first conductive type semiconductor layer 124 are in contact with each other, A second region d4 in contact with the layer 124 and a third region d6 in which the first electrode layer 142 and the first conductivity type semiconductor layer 124 are in contact with each other. The third region d6 may be equal to the width W3 of the first electrode 142. [

When the first insulating layer 142 and the second insulating layer 132 are formed of the same material, the first insulating layer 142 and the second insulating layer 132 are not separated from each other by physical and / It is possible. In this case, the sum of the width of the first region d5 and the width of the second region d4 may be defined as the width of the first region d5 or the width of the second region d4.

When the width of the first region d5 is widened when the recess 128 has the diameter W1 and the inclination angle 5, the third region d6 becomes narrow and the width of the first region d5 becomes narrow The third region d6 can be widened.

The width of the first region d5 may be 5 mu m to 14 mu m. The process margin for securing the first region d5 can be ensured and the reliability of the semiconductor device can be improved because the first region d5 can be secured. The width W3 of the first electrode layer 142 may be reduced when the recess 128 has the diameter W1 and the inclination angle? 5 of the recess, so that the electrical characteristics may be deteriorated.

Therefore, the width of the third region d6 can be determined by adjusting the width of the first region d5 and the width of the second region d4 in order to make the current distribution of the semiconductor device uniform and secure the current injection characteristic .

In addition, when the total area of the recess 128 is large, the area in which the second electrode 146 can be disposed can be reduced. The ratio of the total area of the first electrode 142 to the total area of the second electrode 246 can be determined through the inverse relationship and the density of the electrons and the holes is matched to optimize the current density. 128 and / or the total area of the recess 128 can be freely designed within the above range.

The thickness of the second electrode 146 may be thinner than the thickness of the first insulating layer 131. Therefore, the step coverage characteristics of the second conductive layer 150 and the second insulating layer 132 that surround the second electrode 146 can be ensured and the reliability of the semiconductor device can be improved. The second electrode 146 may have a first separation distance S1 of 1 mu m to 4 mu m with the first insulation layer 131. [ It is possible to secure a process margin in the process of disposing the second electrode 146 between the first insulating layers 131 and thus to improve the electrical characteristics, optical characteristics and reliability of the semiconductor device . When the spacing distance is 4 占 퐉 or less, the entire area in which the second electrode 146 can be arranged can be secured and the operating voltage characteristics of the semiconductor device can be improved.

The second conductive layer 150 may cover the second electrode 146. Accordingly, the second electrode pad 166, the second conductive layer 150, and the second electrode 146 can form one electrical channel.

The second conductive layer 150 completely surrounds the second electrode 146 and may contact the side surface and the upper surface of the first insulating layer 131. The second conductive layer 150 is made of a material having good adhesion to the first insulating layer 131 and includes at least one material selected from the group consisting of Cr, Al, Ti, Ni, and Au, Alloy, and may be a single layer or a plurality of layers.

When the second conductive layer 150 is in contact with the side surface and the upper surface of the first insulating layer 131, the thermal and electrical reliability of the second electrode 146 can be improved. In addition, it may have a reflection function for reflecting upward the light emitted between the first insulating layer 131 and the second electrode 146.

The second conductive layer 150 may be disposed at a first separation distance S1 between the first insulation layer 131 and the second electrode 146. [ The second conductive layer 150 may be in contact with the side surface and the upper surface of the second electrode 146 and the side surfaces and the upper surface of the first insulating layer 131 at the first spacing distance S1. In addition, a region where the second conductive layer 150 and the second conductive semiconductor layer 126 are in contact with each other to form a Schottky junction can be disposed within the first separation distance S1, and by forming a Schottky junction, Dispersion can be facilitated. The resistance between the second conductive layer 150 and the second conductive type semiconductor layer 126 is greater than the resistance between the second electrode 146 and the second conductive type semiconductor layer 126. [ Can be freely placed within a larger configuration.

The second insulating layer 132 may electrically isolate the second electrode 146 and the second conductive layer 150 from the first conductive layer 165. The first conductive layer 165 may be electrically connected to the first electrode 142 through the second insulating layer 132. The second insulating layer 132 and the first insulating layer 131 may be formed of the same material or different materials.

The second conductive layer 150 may electrically connect the second electrode 146 and the second electrode pad 166.

The second electrode 146 may be disposed directly on the second conductive semiconductor layer 127. At this time, since the surface layer of the second conductivity type semiconductor layer 127 may be composed of n-AlGaN or p-AlGaN as described above, the ohmic resistance may be reduced and the light absorption amount may be small.

The second conductive layer 150 may be formed of at least one material selected from the group consisting of Cr, Al, Ti, Ni, and Au, and alloys thereof, and may be a single layer or a plurality of layers .

The first conductive layer 165 and the bonding layer 160 may be disposed along the bottom surface of the semiconductor structure 120 and the shape of the recess 128. [ The first conductive layer 165 may be made of a material having a high reflectivity. Illustratively, the first conductive layer 165 may comprise aluminum. When the electrode layer 165 includes aluminum, it functions to reflect light emitted from the active layer 126 toward the substrate 170 in an upper direction, thereby improving light extraction efficiency. However, the present invention is not limited thereto, and the first conductive layer 165 may provide a function of being electrically connected to the first electrode 142. The first conductive layer 165 may be disposed without a high reflectivity material, such as aluminum and / or silver, in which case the first electrode 142, disposed in the recess 128, A reflective metal layer (not shown) may be disposed between the first conductive layer 165 and the second conductive semiconductor layer 127 and between the first conductive layer 165 and the first conductive layer 165.

The bonding layer 160 may include a conductive material. Illustratively, the bonding layer 160 may comprise a material selected from the group consisting of gold, tin, indium, aluminum, silicon, silver, nickel, and copper, or alloys thereof.

The substrate 170 may be made of a conductive material. Illustratively, substrate 170 may comprise a metal or semiconductor material. The substrate 170 may be a metal having excellent electrical conductivity and / or thermal conductivity. In this case, the heat generated during semiconductor device operation can be quickly dissipated to the outside. Also, when the substrate 170 is made of a conductive material, the first electrode 142 may be supplied with an electric current from the outside through the substrate 170.

The substrate 170 may comprise a material selected from the group consisting of silicon, molybdenum, silicon, tungsten, copper, and aluminum, or alloys thereof.

A second electrode pad 166 may be disposed at one corner of the semiconductor device. The central portion of the second electrode pad 166 is recessed so that the upper surface of the second electrode pad 166 may have a concave portion and a convex portion. A wire (not shown) may be bonded to the concave portion of the upper surface. Accordingly, the bonding area can be widened and the second electrode pad 166 and the wire can be bonded more firmly. The second electrode pad 166 may be electrically connected to the second conductive layer 150 through the passivation layer 180 and the first insulating layer 131.

A passivation layer 180 may be disposed on the top and sides of the semiconductor structure 120. The thickness of the passivation layer 180 may be greater than or equal to 200 nm and less than or equal to 500 nm. When the thickness is not more than 500 nm, the stress applied to the semiconductor device can be reduced, and the optical and electrical reliability of the semiconductor device can be reduced. Or the process time of the semiconductor device is increased, the problem that the unit price of the semiconductor device is increased can be solved.

Unevenness may be formed on the upper surface of the semiconductor structure 120. Such unevenness can improve the extraction efficiency of light emitted from the semiconductor structure 120. The average height of the unevenness may be different depending on the wavelength of ultraviolet light. In the case of UV-C, the height of the unevenness is about 300 nm to 800 nm and the light extraction efficiency can be improved when the average height is 500 nm to 600 nm.

FIG. 10 is a plan view of a semiconductor device according to the first embodiment of the present invention, and FIG. 11 is a plan view of the semiconductor device according to the present invention. FIG. 12 is a plan view of a semiconductor device according to a third embodiment of the present invention, FIG. 13 is a plan view of a semiconductor device according to a fourth embodiment of the present invention, and FIG. 14 Is a graph of light output and WPE of a semiconductor device according to the first to fourth embodiments.

9A, if the GaN-based semiconductor structure 120 emits ultraviolet light, it may include aluminum, and if the aluminum composition of the semiconductor structure 120 is increased, the current dispersion characteristics may deteriorate in the semiconductor structure 120 . In addition, when the active layer 126 emits ultraviolet rays including Al, the amount of light emitted to the side of the active layer 126 increases (TM mode) as compared with a GaN-based blue light emitting device. This TM mode can mainly occur in an ultraviolet semiconductor device.

The ultraviolet semiconductor device has a lower current dispersion characteristic than the blue GaN based semiconductor device. Therefore, the ultraviolet semiconductor device needs to arrange the first electrode 142 relatively larger than the blue GaN-based semiconductor device.

The higher the composition of aluminum, the worse the current dispersion characteristics may be. Referring to FIG. 9A, the current is dispersed only at a point near each of the first electrodes 142, and the current density may be drastically lowered at distant points. Therefore, the effective light-emitting region P2 can be narrowed.

The effective light emitting region P2 can be defined as a region up to the boundary point where the current density is 40% or less based on the current density at the center of the first electrode 142 having the highest current density. For example, the effective light emitting region P2 can be adjusted according to the level of the injection current and the composition of Al within a range of 40 占 퐉 from the center of the recess 128. [

The current density in the low current density region P3 is low and the amount of emitted light may be smaller than that in the effective light emitting region P2. Therefore, the first electrode 142 can be further disposed in the low current density region P3 having a low current density, or the light output can be improved by using the reflective structure.

Generally, in the case of a GaN-based semiconductor device emitting blue light, it is preferable to minimize the area of the recess 128 and the first electrode 142 because the current dispersion property is relatively good. The larger the area of the recess 128 and the first electrode 142 is, the smaller the area of the active layer 126 is. However, in the embodiment, since the composition of aluminum is high and the current dispersion characteristics are relatively low, the area and / or number of the first electrode 142 is increased even if the area of the active layer 126 is sacrificed, Or it may be desirable to arrange the reflective structure in the low current density region P3.

9B, when the number of the recesses 128 increases to 48, the recesses 128 may be arranged in a zigzag manner instead of being arranged straight in the transverse direction. In this case, since the area of the low current density region P3 can be narrowed, most of the active layer 126 can participate in light emission.

10 to 13, when the number of recesses is increased to 79 in FIG. 10, 96 in FIG. 11, 116 in FIG. 12, and 137 in FIG. 13, a low current density region Circle area) can be further reduced.

Table 2 shows the total area (ISO area) of the semiconductor structures of Examples 1 to 4, the area of the p-ohmic electrode (second area), the area of the n-ohmic electrode (first area), the area ratio, Were measured.

The semiconductor structure area (ISO area) may be the maximum horizontal cross-sectional area including the recess area.

The area of the first electrode may be the area of the n-ohmic electrode, which increases as the number of recesses 128 increases, based on the area 100% of the semiconductor structure.

The area of the second electrode may be the area of the p-Ohmic electrode, which decreases as the number of recesses 128 increases, based on 100% area of the semiconductor structure.

In Table 3, the semiconductor structure area (ISO area), the recess area, the area of the second conductivity type semiconductor layer, the area of the first conductive layer, and the area of the second electrode pad in Examples 1 to 4 were measured.

The recess area is the total area of the recess, which increases with the number of recesses based on the area of 100% of the semiconductor structure. Here, the area of each recess may be the largest in the thickness direction.

The area of the second conductivity type semiconductor layer is the total area of the second conductivity type semiconductor layer which decreases as the number of recesses increases, based on the area of 100% of the semiconductor structure.

The area of the first conductive layer is the total area of the first conductive layer which decreases with increasing number of recesses based on 100% of the semiconductor structure.

The second electrode pad is designed to have a constant area regardless of the number of recesses based on 100% of the semiconductor structure.

	Total area of semiconductor structure [%]	First electrode area [%]	Second electrode area [%]	First electrode: second electrode area ratio	Number of recesses
Example 1	100	4.9	62.6	1: 12.7	79
Example 2	100	6.0	56.5	1: 9.41	96
Example 3	100	7.3	49.4	1: 6.76	116
Example 4	100	8.6	41.9	1: 4.87	137

	Total area of semiconductor structure [%]	The recess area [%]	Area of the second conductive type semiconductor layer [%]	Area of first conductive layer [%]	Second electrode pad area [%]
Example 1	100	16	84.0	72.4	4.4
Example 2	100	18.5	81.5	67.1	4.4
Example 3	100	21.5	78.5	60.9	4.4
Example 4	100	24.6	75.4	54.3	4.4

Referring to Examples 1 to 4, it can be seen that as the number of recesses 128 increases, the area of the active layer and the second electrode decreases, and the total area of the recess 128 and the total area of the first electrode gradually increase In Examples 1 to 4, the sizes of the semiconductor elements, the recesses, and the sizes of the first electrodes were the same. Illustratively, the diameter of the recess 128 was made equal to 56 μm, and the diameter of the first electrode was made equal to 42 μm.

The first area where the plurality of first electrodes 142 are in contact with the first conductivity type semiconductor layer 124 may be 4.9% or more and 8.6% or less of the maximum cross-sectional area in the horizontal direction of the semiconductor structure 120.

When the first area of the plurality of first electrodes 142 is 4.9% or more, a sufficient current injection characteristic can be ensured, so that the light output can be ensured. When the area is 8.6% or less, the area of the active layer and the second electrode The operating voltage characteristics and the light output can be improved.

In addition, the total area of the plurality of recesses 128 may be at least 16% and at most 24.6% of the maximum cross-sectional area in the horizontal direction of the semiconductor structure 120. If the total area of the recess 128 does not satisfy the above condition, it may be difficult to control the total area of the first electrode 142 to 4.9% or more and 8.6% or less. In the case where the semiconductor structure 120 is made of AlGaN based material, the current injection characteristic to be injected from the outside into the semiconductor structure 120 and the current diffusion characteristic in the semiconductor structure 120 due to the high resistance of the semiconductor structure 120 May be lower than the GaN-based semiconductor structure 120. Therefore, when the total area of the recesses is 16% or more of the maximum cross-sectional area in the horizontal direction of the semiconductor structure 120, electrical characteristics due to current injection and current diffusion characteristics can be secured. It is possible to ensure the optical characteristics such as light output.

The second area where the second electrode 246 contacts the second conductive type semiconductor layer 127 may be not less than 41.9% and not more than 62.6% of the maximum cross-sectional area in the horizontal direction of the semiconductor structure 120. The second area may be the total area at which the second electrode 246 contacts the second conductive semiconductor layer 127.

The second area for ensuring the operating voltage characteristics of the semiconductor device and securing the injection efficiency of the holes injected into the semiconductor structure 120 may be 42% or more of the maximum cross-sectional area in the horizontal direction of the semiconductor structure 120. In order to ensure a balance between the injection efficiency of electrons injected into the semiconductor structure 120 and the injection efficiency of holes and the injection efficiency of electrons and to ensure the optical and electrical characteristics of the semiconductor elements, Of the maximum cross-sectional area in the horizontal direction of the optical fiber 120.

According to the embodiment, since the surface of the second conductivity type semiconductor layer in contact with the second electrode contains aluminum, the current dispersion efficiency may be relatively lowered. Therefore, it is necessary to improve the current dispersion efficiency by widening the contact area of the second electrode.

14, the second embodiment (# 2) in which the number of recesses 128 is 96, based on the optical output 100% of the first embodiment (# 1) in which the number of recesses 128 is 79, ), The light output was improved by 4% as compared with the first embodiment. In the third embodiment (# 3) in which the number of recesses was increased to 116, the light output was improved by 3% as compared with the first embodiment. However, in the case of the fourth embodiment (# 4) in which the number of recesses is increased to 137, the light output is rather lower than that of the third embodiment.

Also, it can be seen that the power conversion efficiency (Wall-Plug Efficiency) also shows the same tendency as the optical output power. The power conversion efficiency may be output power / input power. Illustratively, the horizontal dotted line may be a desired WPE reference, but is not necessarily limited thereto.

The first area and the second area have an inverse relationship. That is, when the number of recesses is increased in order to increase the number of first electrodes, the area of the second electrode decreases. It can be seen that the first area or the second area is excessively reduced in the first and fourth embodiments, resulting in a decrease in light output.

Referring to FIG. 14, it can be seen that when the number of recesses is larger than 79 and smaller than 137, the optical output power and power conversion efficiency can be relatively high.

Therefore, the ratio of the first area where the first electrodes are in contact with the first conductivity type semiconductor layer and the second area where the second electrode is in contact with the second conductivity type semiconductor layer (first area: second area) is 1 : Greater than 4.87 and less than 1: 12.7.

When the area ratio is larger than 1: 4.87, the second area with respect to the first area can be sufficiently secured. Therefore, the current injection characteristic by the second electrode is improved, so that the balance of electrons and holes injected into the active layer 126 can be secured. Further, the current injection characteristics of the semiconductor element can be improved.

Illustratively, in the case of Example 4, the second area is only about 41.9%, so that the balance of electrons and holes injected into the active layer 126 can not be ensured and current injection characteristics of the semiconductor device may be deteriorated. As a result, the light output of the semiconductor element can be reduced.

The area ratio can be adjusted to be less than 1: 12.7 to secure the first area for the second area. If the area ratio is adjusted to be smaller than 1: 12.7, the current injection characteristic by the first electrode can be improved and the balance of electrons and holes injected into the active layer 126 can be ensured, thereby improving current injection characteristics of the semiconductor device. Illustratively, in the case of the first embodiment, the first area is only about 4.9%, and the current injection efficiency may be lowered.

Further, the maximum area (lower surface) in the horizontal direction of the semiconductor structure and the area ratio of recesses may be larger than 1: 0.16 and smaller than 1: 0.246. If the area ratio is larger than 1: 0.16, a sufficient first area can be ensured and current injection characteristics by the first electrode can be improved. Further, when the area ratio is smaller than 1: 0.246, the second area can be secured and the current injection characteristic can be improved.

FIG. 15 is a conceptual view of a semiconductor device according to a fifth embodiment of the present invention, and FIG. 16 is a plan view of FIG.

Referring to FIG. 15, the above-described structure of the light emitting structure 120 may be applied as it is. The plurality of recesses 128 may extend to a portion of the first conductivity type semiconductor layer 124 through the second conductivity type semiconductor layer 127 and the active layer 126.

The first electrode 142 may be disposed on the upper surface of the recess 128 and may be electrically connected to the first conductive semiconductor layer 124. The second electrode 146 may be disposed under the second conductive semiconductor layer 127 and electrically connected thereto. At this time, since the surface layer of the second conductivity type semiconductor layer 127 may be composed of n-AlGaN or p-AlGaN as described above, the ohmic resistance may be reduced and the light absorption amount may be small.

The first insulating layer 131 may electrically isolate the first electrode 142 from the active layer 126 and the second conductive type semiconductor layer 127. The first insulating layer 131 may electrically isolate the second electrode 146 and the second conductive layer 150 from the first conductive layer 165.

When the first insulating layer 131 performs the insulating function, light emitted toward the side surface of the active layer 126 may be reflected upward to improve light extraction efficiency. As described later, in the ultraviolet semiconductor device, the larger the number of the recesses 128, the more effective the light extraction efficiency.

The second conductive layer 150 may cover the second electrode 146. Accordingly, the second electrode pad 166, the second conductive layer 150, and the second electrode 146 can form one electrical channel.

The second conductive layer 150 completely surrounds the second electrode 146 and may contact the side surface and the upper surface of the first insulating layer 131. The second conductive layer 150 is made of a material having good adhesion to the first insulating layer 131 and includes at least one material selected from the group consisting of Cr, Al, Ti, Ni, Au, And may be a single layer or a plurality of layers.

When the second conductive layer 150 is in contact with the side surface and the upper surface of the first insulating layer 131, the thermal and electrical reliability of the second electrode 146 can be improved. In addition, it may have a reflection function for reflecting upward the light emitted between the first insulating layer 131 and the second electrode 146.

The second insulating layer 132 may electrically isolate the second electrode 146 and the second conductive layer 150 from the first conductive layer 165. The first conductive layer 165 may be electrically connected to the first electrode 142 through the second insulating layer 132.

The first conductive layer 165 and the bonding layer 160 may be disposed along the bottom surface of the light emitting structure 120 and the shape of the recess 128. The first conductive layer 165 may be made of a material having a high reflectivity. Illustratively, the first conductive layer 165 may comprise aluminum. When the first conductive layer 165 includes aluminum, it functions to reflect the light emitted from the active layer 126 to the upper portion, thereby improving the light extraction efficiency.

The bonding layer 160 may include a conductive material. Illustratively, the bonding layer 160 may comprise a material selected from the group consisting of gold, tin, indium, aluminum, silicon, silver, nickel, and copper, or alloys thereof.

The substrate 170 may be made of a conductive material. Illustratively, substrate 170 may comprise a metal or semiconductor material. The substrate 170 may be a metal having excellent electrical conductivity and / or thermal conductivity. In this case, the heat generated during semiconductor device operation can be quickly dissipated to the outside.

The substrate 170 may comprise a material selected from the group consisting of silicon, molybdenum, silicon, tungsten, copper, and aluminum, or alloys thereof.

Irregularities may be formed on the upper surface of the light emitting structure 120. This unevenness can improve the extraction efficiency of light emitted from the light emitting structure 120. The average height may vary depending on the wavelength of ultraviolet light. In the case of UV-C, the height of the unevenness is about 300 nm to 800 nm, and the light extraction efficiency can be improved when the average height is 500 nm to 600 nm.

The semiconductor device may include a side reflector Z1 disposed at the edge. The side reflective portion Z1 may be formed by protruding the second conductive layer 150, the first conductive layer 165, and the substrate 170 in the thickness direction (Y axis direction). Referring to FIG. 16, the side reflector Z1 may be disposed along the edge of the semiconductor device, and may surround the light emitting structure.

The second conductive layer 150 of the side reflecting portion Z1 protrudes higher than the active layer 126 and can upward reflect the light emitted from the active layer 126. [ Accordingly, even if a separate reflection layer is not formed, the light emitted in the horizontal direction (X-axis direction) due to the TM mode at the outermost periphery can be upwardly reflected.

The angle of inclination of the side reflector Z1 may be greater than 90 degrees and less than 145 degrees. The inclination angle may be an angle formed by the second conductive layer 150 and the horizontal plane (XZ plane). If the angle is less than 90 degrees or greater than 145 degrees, the efficiency of reflecting the light traveling toward the side toward the image side may decrease.

FIG. 17 is a conceptual view of a semiconductor device package according to an embodiment of the present invention, FIG. 18 is a plan view of a semiconductor device package according to an embodiment of the present invention, and FIG. 19 is a modification of FIG.

17, the semiconductor device package comprises a body 2 formed with a groove 3, a semiconductor element 1 disposed on the body 2, and a semiconductor element 1 disposed on the body 2 and electrically connected to the semiconductor element 1 And may include a pair of lead frames 5a and 5b connected thereto. The semiconductor element 1 may include all of the structures described above.

The body 2 may include a material or a coating layer that reflects ultraviolet light. The body 2 can be formed by laminating a plurality of layers 2a, 2b, 2c, 2d and 2e. The plurality of layers 2a, 2b, 2c, 2d and 2e may be the same material or may comprise different materials.

The groove 3 may be formed so as to be wider as it is away from the semiconductor element, and a step 3a may be formed on the inclined surface.

The light-transmitting layer 4 may cover the groove 3. [ The light-transmitting layer 4 may be made of a glass material, but is not limited thereto. The light-transmitting layer 4 is not particularly limited as long as it is a material capable of effectively transmitting ultraviolet light. The inside of the groove 3 may be an empty space.

18, the semiconductor element 10 is disposed on the first lead frame 5a and can be connected to the second lead frame 5b by a wire. At this time, the second lead frame 5b may be arranged to surround the side surface of the first lead frame.

Referring to FIG. 19, a plurality of semiconductor elements 10a, 10b, 10c, and 10d may be disposed in the semiconductor device package. At this time, the lead frame may include the first to fifth lead frames 5a, 5b, 5c, 5d and 5e.

The first semiconductor element 10a may be disposed on the first lead frame 5a and connected to the second lead frame 5b by a wire. The second semiconductor element 10b may be disposed on the second lead frame 5b and connected to the third lead frame 5c by a wire. The third semiconductor element 10c may be disposed on the third lead frame 5c and connected to the fourth lead frame 5d by a wire. The fourth semiconductor element 10d may be disposed on the fourth lead frame 5d and connected to the fifth lead frame 5e by a wire.

Semiconductor devices can be applied to various types of light source devices. Illustratively, the light source device may be a concept comprising a lighting device, and a display device, a vehicle lamp, and the like. That is, semiconductor devices can be applied to various electronic devices arranged in a case to provide light.

The illumination device may include a light source module including a substrate and semiconductor elements of the embodiment, a heat dissipation unit that dissipates heat of the light source module, and a power supply unit that processes or converts an electrical signal provided from the outside and provides the light source module. Further, the lighting device may include a lamp, a head lamp, or a street lamp or the like.

The display device may include a bottom cover, a reflector, a light emitting module, a light guide plate, an optical sheet, a display panel, an image signal output circuit, and a color filter. The bottom cover, the reflector, the light emitting module, the light guide plate, and the optical sheet can constitute a backlight unit.

The reflector is disposed on the bottom cover, and the light emitting module can emit light. The light guide plate is disposed in front of the reflection plate to guide the light emitted from the light emitting module forward, and the optical sheet may include a prism sheet or the like and be disposed in front of the light guide plate. The display panel is disposed in front of the optical sheet, and the image signal output circuit supplies an image signal to the display panel, and the color filter can be disposed in front of the display panel.

The semiconductor device can be used as a backlight unit of an edge type when used as a backlight unit of a display device or as a backlight unit of a direct-bottom type.

The semiconductor device may be a laser diode other than the light emitting diode described above.

The laser diode may include the first conductivity type semiconductor layer, the active layer and the second conductivity type semiconductor layer having the above-described structure, like the light emitting element. Then, an electro-luminescence (electroluminescence) phenomenon in which light is emitted when an electric current is applied after bonding the p-type first conductivity type semiconductor and the n-type second conductivity type semiconductor is used, There are differences in the directionality and phase of light. That is, the laser diode can emit light having one specific wavelength (monochromatic beam) with the same phase and in the same direction by using a phenomenon called stimulated emission and a constructive interference phenomenon. It can be used for optical communication, medical equipment and semiconductor processing equipment.

As the light receiving element, a photodetector, which is a kind of transducer that detects light and converts the intensity of the light into an electric signal, is exemplified. As photodetectors, photodetectors (silicon, selenium), photodetectors (cadmium sulfide, cadmium selenide), photodiodes (for example, visible blind spectral regions or PDs with peak wavelengths in the true blind spectral region) A transistor, a photomultiplier tube, a phototube (vacuum, gas-filled), and an IR (Infra-Red) detector, but the embodiment is not limited thereto.

In addition, a semiconductor device such as a photodetector may be fabricated using a direct bandgap semiconductor, which is generally excellent in photo-conversion efficiency. Alternatively, the photodetector has a variety of structures, and the most general structure includes a pinned photodetector using a pn junction, a Schottky photodetector using a Schottky junction, and a metal-semiconductor metal (MSM) photodetector have.

The photodiode, like the light emitting device, may include the first conductivity type semiconductor layer having the structure described above, the active layer, and the second conductivity type semiconductor layer, and may have a pn junction or a pin structure. The photodiode operates by applying reverse bias or zero bias. When light is incident on the photodiode, electrons and holes are generated and a current flows. At this time, the magnitude of the current may be approximately proportional to the intensity of the light incident on the photodiode.

A photovoltaic cell or a solar cell is a type of photodiode that can convert light into current. The solar cell, like the light emitting device, may include the first conductivity type semiconductor layer, the active layer and the second conductivity type semiconductor layer having the above-described structure.

In addition, it can be used as a rectifier of an electronic circuit through a rectifying characteristic of a general diode using a p-n junction, and can be applied to an oscillation circuit or the like by being applied to a microwave circuit.

In addition, the above-described semiconductor element is not necessarily implemented as a semiconductor, and may further include a metal material as the case may be. For example, a semiconductor device such as a light receiving element may be implemented using at least one of Ag, Al, Au, In, Ga, N, Zn, Se, P, or As, Or may be implemented using a doped semiconductor material or an intrinsic semiconductor material.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (15)

1. A semiconductor structure including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer;

   A first electrode electrically connected to the first conductive semiconductor layer; And

   And a second electrode electrically connected to the second conductive semiconductor layer,

   Wherein the semiconductor structure includes a third conductivity type semiconductor layer disposed between the second conductivity type semiconductor layer and the second electrode,

   Wherein the third conductivity type semiconductor layer and the first conductivity type semiconductor layer include an n-type dopant,

   Wherein the second conductivity type semiconductor layer includes a p-type dopant,

   The thickness of the third conductivity type semiconductor layer is thinner than the thickness of the first conductivity type semiconductor layer,

   Wherein the dopant concentration of the third conductivity type semiconductor layer is higher than the dopant concentration of the first conductivity type semiconductor layer,

   Wherein a ratio of an aluminum composition of the third conductivity type semiconductor layer to an aluminum composition of the first conductivity type semiconductor layer is 1: 0.71 to 1: 3.5.
2. The method according to claim 1,

   Wherein the first conductivity type semiconductor layer, the active layer, the second conductivity type semiconductor layer, and the third conductivity type semiconductor layer comprise aluminum.
3. 3. The method of claim 2,

   Wherein an aluminum composition of the third conductivity type semiconductor layer is higher than an aluminum composition of the active layer and the first conductivity type semiconductor layer.
4. 3. The method of claim 2,

   And the aluminum composition of the third conductivity type semiconductor layer is lower than the aluminum composition of the active layer and the first conductivity type semiconductor layer.
5. The method according to claim 1,

   Wherein the first conductive semiconductor layer includes a first sub-semiconductor layer, a second sub-semiconductor layer, and an intermediate layer disposed between the first sub-semiconductor layer and the second sub-

   Wherein an aluminum composition of the intermediate layer is lower than an aluminum composition of the first sub semiconductor layer and the second sub semiconductor layer.
6. 6. The method of claim 5,

   Wherein the aluminum composition of the intermediate layer is higher than the aluminum composition of the well layer of the active layer.
7. The method according to claim 6,

   Wherein an aluminum composition of the third conductivity type semiconductor layer is higher than an aluminum composition of the well layer and lower than an aluminum composition of the intermediate layer.
8. The method according to claim 1,

   Wherein the second conductivity type semiconductor layer includes a third sub-semiconductor layer whose aluminum composition decreases in a thickness direction,

   And the third conductivity type semiconductor layer is disposed between the third sub-semiconductor layer and the second electrode.
9. 9. The method of claim 8,

   Wherein the second conductivity type semiconductor layer includes a fourth sub-semiconductor layer disposed between the third sub-semiconductor layer and the active layer, and the fourth sub-semiconductor layer has a constant aluminum composition in the thickness direction.
10. The method according to claim 1,

    And the change in aluminum composition between the second conductivity type semiconductor layer and the third conductivity type semiconductor layer is discontinuous.
11. The method according to claim 1,

    Wherein the second conductivity type semiconductor layer and the third conductivity type semiconductor layer have the same aluminum composition.
12. The method according to claim 1,

    The doping concentration of the first conductivity type semiconductor layer is 1 × 10 ¹⁸ / cm ³ to 2 × 10 ²⁰ / cm ³ ,

    And the doping concentration of the third conductivity type semiconductor layer is 2 x 10 ¹⁹ / cm ³ to 3 x 10 ²⁰ / cm ³ .
13. The method according to claim 1,

    Wherein the semiconductor structure includes the third conductive type semiconductor layer, the second conductive type semiconductor layer, and a plurality of recesses penetrating the active layer to a partial region of the first conductive type semiconductor layer,

    Wherein the first electrode is disposed inside the recess,

    And the second electrode contacts the third conductive type semiconductor layer.
14. 14. The method of claim 13,

    A first conductive layer electrically connected to the first electrode,

    A second conductive layer electrically connected to the second electrode,

    A second insulating layer disposed between the first conductive layer and the second conductive layer, and

    And a conductive substrate disposed under the second conductive layer.
15. 14. The method of claim 13,

    Wherein an area ratio of the lower surface of the semiconductor structure to the plurality of recesses is greater than 1: 0.16 and less than 1: 0.246.

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