KR20110120080A

KR20110120080A - Light emitting device, method for fabricating the same, light emitting device package and lighting system including the same

Info

Publication number: KR20110120080A
Application number: KR1020100039598A
Authority: KR
Inventors: 황성민
Original assignee: 엘지이노텍 주식회사
Priority date: 2010-04-28
Filing date: 2010-04-28
Publication date: 2011-11-03

Abstract

PURPOSE: A light emitting device, a light emitting device manufacturing method, a light emitting device package, and a lighting system thereof are provided to improve light extraction efficiency by effectively adjusting a current flow, thereby improving the reliability of light emitting device. CONSTITUTION: A light emitting structure(110) is arranged on a substrate(105). The light emitting structure comprises a first conductive semiconductor layer(112), an active layer(114), and a second conductive semiconductor layer(116). A second conductive region(120) is arranged in a partial region of the second conductive semiconductor layer. A second electrode(146) is arranged on the second conductive semiconductor layer. A first electrode(142) is arranged on the exposed first conductive semiconductor layer.

Description

LIGHT EMITTING DEVICE, METHOD FOR FABRICATING THE SAME, LIGHT EMITTING DEVICE PACKAGE AND LIGHTING SYSTEM INCLUDING THE SAME}

Embodiments relate to a light emitting device, a method of manufacturing the light emitting device, a light emitting device package and an illumination system.

A light emitting device (LED) may be generated by combining elements of group III and group V on a periodic table of a p-n junction diode having a characteristic in which electrical energy is converted into light energy. LED can realize various colors by adjusting the composition ratio of compound semiconductors.

On the other hand, according to the prior art, there is a problem in that the lifespan and reliability due to current crowding is reduced.

In addition, according to the related art, current flows in the reverse direction during electrostatic discharge (ESD), thereby causing damage to the active layer, which is a light emitting region. To solve this problem, a Zener diode is applied to a package. When mounted, there is a problem that absorption of the amount of light occurs.

Embodiments provide a light emitting device, a method of manufacturing a light emitting device, a light emitting device package, and an illumination system capable of improving current spreading efficiency as well as improving light extraction efficiency.

Embodiments provide a light emitting device, a manufacturing method of a light emitting device, a light emitting device package, and an illumination system capable of preventing damage caused by electrostatic discharge without loss of light absorption.

The light emitting device according to the embodiment includes a substrate; A light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the substrate, wherein the light emitting structure exposes a portion of the first conductive semiconductor layer to an upper portion thereof; A second conductivity type region having a higher concentration than the second conductivity type semiconductor layer in a portion of the second conductivity type semiconductor layer; A second electrode on the second conductive semiconductor layer; And a first electrode on the exposed first conductive semiconductor layer.

In addition, the manufacturing method of the light emitting device according to the embodiment comprises the steps of forming a light emitting structure including a first conductive semiconductor layer, an active layer, a second conductive semiconductor layer on a substrate; Mesa-etching the light emitting structure to expose a portion of the first conductivity type semiconductor layer to the top; Forming a second conductivity type region at a higher concentration than the second conductivity type semiconductor layer in a portion of the second conductivity type semiconductor layer; And forming a second electrode on the second conductive semiconductor layer and a first electrode on the exposed first conductive semiconductor layer.

In addition, the light emitting device package according to the embodiment includes a package body; The light emitting device disposed on the package body; And an electrode electrically connecting the package body and the light emitting device.

In addition, the lighting system according to the embodiment includes a light emitting module unit having the light emitting device package.

According to the light emitting device, the method of manufacturing the light emitting device, the light emitting device package, and the lighting system according to the embodiment, light extraction efficiency can be increased by controlling the current flow.

Further, according to the embodiment, the reliability of the light emitting device can be improved by current spreading.

In addition, according to the embodiment, it is possible to prevent electrostatic discharge (ESD) of the LED without loss of light absorption.

1 is a cross-sectional view of a light emitting device according to an embodiment.
2 and 3 are conceptual diagrams of electric field induction in the light emitting device according to the embodiment.
4 to 6 are cross-sectional views of a method of manufacturing a light emitting device according to the embodiment.
7 is a cross-sectional view of a light emitting device package according to the embodiment.
8 is a perspective view of a lighting unit according to an embodiment;
9 is an exploded perspective view of the backlight unit according to the embodiment;

In the description of an embodiment according to the present invention, each layer (film), region, pattern or structure may be “on / over” or “below” the substrate, each layer (film), region, pad or pattern. In the case described as being formed under, "on / over" and "under" are formed "directly" or "indirectly" through another layer. It includes everything that is done. In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

(Example)

1 is a cross-sectional view of a light emitting device according to an embodiment.

The light emitting device 100 according to the embodiment includes a substrate 105 and a first conductive semiconductor layer 112, an active layer 114, and a second conductive semiconductor layer 116 on the substrate 105. The light emitting structure 110 is formed to expose a portion of the first conductivity type semiconductor layer 112 and the second conductivity type semiconductor layer 116 in a portion of the second conductivity type semiconductor layer 116. On the second conductive region 120 formed on the second conductive region 120, the second electrode 146 formed on the second conductive semiconductor layer 116, and the exposed first conductive semiconductor layer 112. It may include a first electrode 142 formed on.

The second conductivity type region 120 may be formed so as not to contact the mesa edge region.

In addition, the second conductivity type region 120 may be formed between the second electrode 146 and the mesa edge region.

The embodiment may further include a transparent electrode 130 formed on the second conductive semiconductor layer 116.

The embodiment is a structure for increasing the breakdown voltage, and may form the second conductive region 120 in the second conductive semiconductor layer 116 around the mesa edge to induce an electric field. have.

The second conductivity type region 120 is a region having a greater doping concentration than the doping concentration of the second conductivity type semiconductor layer 116 and may be formed by ion implantation or diffusion.

According to an embodiment, through this structure, the concentrated strong electric field generated in the mesa edge region according to the prior art is induced or relaxed to the second conductive region 120 to prevent avalanche breakdown due to the strong electric field. It can be reduced and consequently the breakdown voltage can be increased and the leakage current can be reduced.

In addition, the embodiment may improve the current spreading of the LED by forming a high concentration of the second conductivity type region 120 between the second electrode 146 and the mesa edge region, thereby inducing light quantity improvement.

2 and 3 are conceptual views of electric field induction in the light emitting device according to the embodiment.

LED destruction due to electrostatic discharge occurs during semiconductor reverse voltage. Charged at reverse voltage, a strong electric field is induced in the LED active region.

And, during electrostatic discharge, carriers (electrons, holes) are accelerated to collide with atoms to create other carriers, and the resulting carriers produce numerous carriers. This phenomenon is called avalanche breakdown. If the charge is induced to a strong stationary field and the electrostatic charge is exceeded by the semiconductor, the avalanche breakdown eventually leads to the destruction of the LED semiconductor.

According to the embodiment, as the doping concentrations N _A and N _D become larger as shown in FIGS. 2 and 3 and the following equations, a strong electric field is induced by the ionized charge in the depletion region.

Accordingly, according to the embodiment, the concentrated strong electric field generated in the mesa edge region may be induced or relaxed to the second conductive region 120 to reduce the avalanche breakdown caused by the strong electric field, and consequently, This increases the breakdown voltage and reduces the leakage current.

Hereinafter, a method of manufacturing a light emitting device according to an embodiment will be described with reference to FIGS. 4 to 6. The light emitting device in the embodiment may be formed of III-V group materials such as GaN, GaAs, GaAsP, GaP, but is not limited thereto. In addition, the order of the process described below is not limited, and the order may be different.

First, the substrate 105 is prepared as shown in FIG. 4. The substrate 105 may be a sapphire (Al ₂ O ₃ ) substrate, a SiC substrate, but is not limited thereto. Impurities on the surface may be removed by performing wet cleaning on the substrate 105.

Thereafter, the light emitting structure 110 including the first conductive semiconductor layer 112, the active layer 114, and the second conductive semiconductor layer 116 is formed on the substrate 105.

In an embodiment, an undoped semiconductor layer (not shown) may be formed on the substrate 105, and a first conductive semiconductor layer 112 may be formed on the undoped semiconductor layer. For example, an undoped GaN layer may be formed on the substrate 105, and an n-type GaN layer may be formed to form the first conductive semiconductor layer 112.

The first conductive semiconductor layer 112 may be formed of any one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP.

The first conductive semiconductor layer 112 may form an N-type GaN layer using a chemical vapor deposition method (CVD), molecular beam epitaxy (MBE), or sputtering or hydroxide vapor phase epitaxy (HVPE). . In addition, the first conductive semiconductor layer 110 may include a silane including n-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and silicon (Si) in the chamber. The gas SiH ₄ may be injected and formed.

Thereafter, an active layer 114 is formed on the first conductivity type semiconductor layer 112. The active layer 114 may have a quantum well structure in which nitride semiconductor thin film layers having different energy bands are alternately stacked one or more times. For example, the active layer 114 is injected with trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) to form an InGaN / GaN, InGaN / InGaN structure. The multi quantum well structure may be formed, but is not limited thereto.

Thereafter, a second conductive semiconductor layer 116 is formed on the active layer 114. For example, the second conductive semiconductor layer 116 may be formed by injecting trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn). May be formed, but is not limited thereto.

The active layer 114 may be formed of any one or more of InGaN / GaN, InGaN / InGaN, AlGaN / GaN, InAlGaN / GaN, GaAs, / AlGaAs (InGaAs), and GaP / AlGaP (InGaP).

The second conductivity type semiconductor layer 116 is a bicetyl cyclone containing p-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and magnesium (Mg) in the chamber. Pentadienyl magnesium (EtCp ₂ Mg) {Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ } may be injected to form a p-type GaN layer, but is not limited thereto.

Next, the light emitting structure 110 may be mesa-etched to expose a portion of the first conductive semiconductor layer 112 upward. For example, the second conductive semiconductor layer 116 is etched from the second conductive semiconductor layer 116 to a region where the first electrode 142 is to be formed using a predetermined etching pattern (not shown) as a mask, and then passes through the active layer 114. A portion of the upper surface of the type semiconductor layer 112 may be exposed.

Next, as shown in FIG. 5, the second conductivity type region 120 may be formed on the light emitting structure 110. For example, the second conductivity type region 120 may be formed in a portion of the second conductivity type semiconductor layer 116 at a higher concentration than the second conductivity type semiconductor layer 116.

For example, the second conductivity type region 120 may have a doping concentration of about 10 to 100 times or more than the second conductivity type semiconductor layer 116, but is not limited thereto.

The second conductivity type region 120 may be formed so as not to contact the mesa edge region, and the second conductivity type region 120 may be formed between the second electrode 146 and the mesa edge region to be formed later. But it is not limited thereto.

Next, the transparent electrode 130 may be formed on the second conductive semiconductor layer 116 in which the second conductive region 120 is formed in FIG. 6. For example, the transparent electrode 130 may be formed by stacking a single metal, a metal alloy, a metal oxide, or the like in multiple layers. For example, the ohmic layer may include ITO, IZO (In-ZnO), GZO (Ga-ZnO), AZO (Al-ZnO), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), IrOx, RuOx. , RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au / ITO, Ni, Pt, Cr, Ti, Ag, and the like, and may be formed, but are not limited thereto.

Next, a first electrode 142 may be formed on the exposed first conductive semiconductor layer 112, and a second electrode 146 may be formed on the transparent electrode 130.

The first electrode 142 and the second electrode 146 are formed of titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), and tungsten (W). It may be formed of at least one, but is not limited thereto.

7 is a cross-sectional view of a light emitting device package 200 according to the embodiment.

Referring to FIG. 7, the light emitting device package according to the embodiment may include a body portion 205, a fourth electrode layer 210 and a fifth electrode layer 220 installed on the body portion 205, and the body portion 205. The light emitting device 100 is installed at and electrically connected to the fourth electrode layer 210 and the fifth electrode layer 220, and a molding member 240 surrounding the light emitting device 100 is included.

The body 205 may include a silicon material, a synthetic resin material, or a metal material, and an inclined surface may be formed around the light emitting device 100.

The fourth electrode layer 210 and the fifth electrode layer 220 are electrically separated from each other, and serve to provide power to the light emitting device 100. In addition, the fourth electrode layer 210 and the fifth electrode layer 220 may serve to increase light efficiency by reflecting light generated from the light emitting device 100, and may be generated in the light emitting device 100. It may also serve to release heat to the outside.

The light emitting device 100 may be a horizontal type light emitting device illustrated in FIG. 1, but is not limited thereto. The light emitting device 100 may be installed on the body portion 205.

The light emitting device 100 may be electrically connected to the fourth electrode layer 210 and / or the fifth electrode layer 220 through a wire 230. In the embodiment, the light emitting device 100 of the horizontal type is illustrated. As such, two wires 230 are used. As another example, when the light emitting device 100 is a flip chip type light emitting device, the wire 230 may not be used.

The molding member 240 may surround the light emitting device 100 to protect the light emitting device 100. In addition, the molding member 240 may include a phosphor to change the wavelength of the light emitted from the light emitting device 100.

The light emitting device package according to the embodiment may be applied to an illumination system. The lighting system includes a lighting unit shown in FIG. 8 and a back light unit shown in FIG. 9, and may include a traffic light, a vehicle headlight, a signboard, and the like.

8 is a perspective view 1100 of a lighting unit according to an embodiment.

Referring to FIG. 8, the lighting unit 1100 is installed in the case body 1110, the light emitting module unit 1130 installed in the case body 1110, and the case body 1110, and supplies power from an external power source. It may include a connection terminal 1120 provided.

The case body 1110 may be formed of a material having good heat dissipation characteristics. For example, the case body 1110 may be formed of a metal material or a resin material.

The light emitting module unit 1130 may include a substrate 1132 and at least one light emitting device package 200 mounted on the substrate 1132.

The substrate 1132 may be a circuit pattern printed on an insulator, and for example, a general printed circuit board (PCB), a metal core PCB, a flexible PCB, a ceramic PCB, and the like. It may include.

In addition, the substrate 1132 may be formed of a material that reflects light efficiently, or the surface may be formed of a color that reflects light efficiently, for example, white, silver, or the like.

The at least one light emitting device package 200 may be mounted on the substrate 1132. Each of the light emitting device packages 200 may include at least one light emitting diode (LED) 100. The light emitting diodes 100 may include colored light emitting diodes emitting red, green, blue, or white colored light, and UV light emitting diodes emitting ultraviolet (UV) light.

The light emitting module unit 1130 may be disposed to have a combination of various light emitting device packages 200 to obtain color and luminance. For example, a white light emitting diode, a red light emitting diode, and a green light emitting diode may be combined to secure high color rendering (CRI).

The connection terminal 1120 may be electrically connected to the light emitting module unit 1130 to supply power. According to FIG. 8, the connection terminal 1120 is inserted into and coupled to an external power source in a socket manner, but is not limited thereto. For example, the connection terminal 1120 may be formed in a pin shape and inserted into an external power source, or may be connected to the external power source by a wire.

9 is an exploded perspective view 1200 of a backlight unit according to an embodiment.

The backlight unit 1200 according to the embodiment includes a light guide plate 1210, a light emitting module unit 1240 that provides light to the light guide plate 1210, a reflective member 1220 under the light guide plate 1210, and the light guide plate. 1210, a bottom cover 1230 for accommodating the light emitting module unit 1240 and the reflective member 1220, but is not limited thereto.

The light guide plate 1210 serves to surface light by diffusing light. The light guide plate 1210 is made of a transparent material, for example, an acrylic resin series such as polymethyl metaacrylate (PMMA), polyethylene terephthlate (PET), polycarbonate (PC), cycloolefin copolymer (COC), and polyethylene naphthalate (PEN). It may include one of the resins.

The light emitting module unit 1240 provides light to at least one side of the light guide plate 1210 and ultimately serves as a light source of a display device in which the backlight unit is installed.

The light emitting module unit 1240 may be in contact with the light guide plate 1210, but is not limited thereto. Specifically, the light emitting module unit 1240 includes a substrate 1242 and a plurality of light emitting device packages 200 mounted on the substrate 1242, wherein the substrate 1242 is connected to the light guide plate 1210. It may be encountered, but is not limited thereto.

The substrate 1242 may be a printed circuit board (PCB) including a circuit pattern (not shown). However, the substrate 1242 may include not only a general PCB but also a metal core PCB (MCPCB, Metal Core PCB), a flexible PCB (FPCB, Flexible PCB), and the like, but is not limited thereto.

The plurality of light emitting device packages 200 may be mounted on the substrate 1242 such that a light emitting surface on which light is emitted is spaced apart from the light guide plate 1210 by a predetermined distance.

The reflective member 1220 may be formed under the light guide plate 1210. The reflective member 1220 may improve the luminance of the backlight unit by reflecting the light incident on the lower surface of the light guide plate 1210 upward. The reflective member 1220 may be formed of, for example, PET, PC, or PVC resin, but is not limited thereto.

The bottom cover 1230 may accommodate the light guide plate 1210, the light emitting module unit 1240, the reflective member 1220, and the like. To this end, the bottom cover 1230 may be formed in a box shape having an upper surface opened, but is not limited thereto.

The bottom cover 1230 may be formed of a metal material or a resin material, and may be manufactured using a process such as press molding or extrusion molding.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Accordingly, the contents of such combinations and modifications should be construed as being included in the scope of the embodiments.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. Those skilled in the art to which the present invention pertains will be illustrated as above without departing from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

Claims

Board;
A light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the substrate, wherein the light emitting structure exposes a portion of the first conductive semiconductor layer to an upper portion thereof;
A second conductivity type region having a higher concentration than the second conductivity type semiconductor layer in a portion of the second conductivity type semiconductor layer;
A second electrode on the second conductive semiconductor layer; And
And a first electrode on the exposed first conductive semiconductor layer.

The method according to claim 1,
The second conductivity type region,
A light emitting device is formed so as not to contact the mesa edge region.

The method according to claim 1,
The second conductivity type region,
The light emitting device is formed between the second electrode and the mesa edge region.

The method according to claim 1,
The light emitting device further comprises a transparent electrode formed on the second conductive semiconductor layer.

Forming a light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on a substrate;
Mesa-etching the light emitting structure to expose a portion of the first conductivity type semiconductor layer to the top;
Forming a second conductivity type region at a higher concentration than the second conductivity type semiconductor layer in a portion of the second conductivity type semiconductor layer; And
And forming a second electrode on the second conductive semiconductor layer and a first electrode on the exposed first conductive semiconductor layer.

The method of claim 5,
Forming the second conductivity type region,
A method of manufacturing a light emitting device that is formed so as not to contact the mesa edge region.

The method of claim 5,
Forming the second conductivity type region,
Method of manufacturing a light emitting device formed by ion implantation or diffusion.

The method of claim 5,
The second conductivity type region,
The manufacturing method of the light emitting device is formed between the second electrode and the mesa edge region.

Package body;
The light emitting device of any one of claims 1 to 4 disposed on the package body; And
Light emitting device package comprising; an electrode for electrically connecting the package body and the light emitting device.

An illumination system comprising a light emitting module unit having a light emitting device package of claim 9.