CN212323021U

CN212323021U - Nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer

Info

Publication number: CN212323021U
Application number: CN202022122249.3U
Authority: CN
Inventors: 高芳亮; 杨金铭
Original assignee: Shenzhen Sanhang Industrial Technology Research Institute; Shenzhen Angde Global Technology Co ltd
Current assignee: Shenzhen Sanhang Industrial Technology Research Institute; Shenzhen Angde Global Technology Co ltd
Priority date: 2020-09-24
Filing date: 2020-09-24
Publication date: 2021-01-08
Anticipated expiration: 2030-09-24

Abstract

The utility model discloses a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer, include: grow on the low temperature AlN layer on the r face sapphire substrate, grow high temperature AlN layer on the low temperature AlN layer, grow on non-doping a face AlGaN buffer layer on the high temperature AlN layer, grow on n type doping a face AlGaN layer on the non-doping a face AlGaN layer, grow and be in a face AlGaN multiple quantum well layer on the n type doping a face AlGaN layer, grow and be in electron barrier layer on the a face AlGaN multiple quantum well layer, grow and be in p type doping AlGaN film on the electron barrier layer, the utility model discloses the nonpolar AlGaN base deep ultraviolet LED epitaxial wafer that prepares defect density is low, crystal quality is good, and electricity, optical property are good.

Description

Nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer

Technical Field

The utility model relates to a semiconductor device technical field, in particular to nonpolar AlGaN base deep ultraviolet LED epitaxial wafer.

Background

The deep ultraviolet light has wide application prospect in the fields of national defense technology, information technology, bio-pharmaceuticals, environmental monitoring, public health, sterilization, disinfection and the like. The traditional ultraviolet light sources adopted at present are gas lasers and mercury lamps, but have the defects of large volume, high energy consumption, pollution and the like. An AlGaN-based compound semiconductor ultraviolet Light Emitting Diode (LED) is a solid ultraviolet light source and has the advantages of small volume, high efficiency, long service life, environmental friendliness, low energy consumption, no pollution and the like. The AlGaN material with high Al component is an irreplaceable material system for preparing high-performance deep ultraviolet LEDs, has great requirements in civil and military aspects, such as the medical and health fields of sterilization, cancer detection, skin disease treatment and the like, and has the advantages of no mercury pollution, adjustable wavelength, small volume, good integration, low energy consumption, long service life and the like.

Most of the conventional AlGaN-based deep ultraviolet LED structures are grown on a c-plane sapphire substrate. However, since the AlGaN material that is epitaxial on c-plane sapphire is generally c-plane and the c-plane nitride material is a polar material, an extremely strong polarization electric field exists in the AlGaN-based deep ultraviolet LED. The polarizing electric field results from spontaneous polarization and piezoelectric polarization along the c-axis direction. Due to the polarization, the energy band of a multi-quantum well region of the deep ultraviolet LED is seriously bent, the wave functions of electrons and holes are separated in space, and the separation causes the effective recombination probability of the electron holes in an active region to be reduced, so that the luminous efficiency of the AlGaN-based LED is influenced. Meanwhile, the carrier transport is blocked by the polarized electric field, and finally, the carrier distribution is not uniform. Therefore, it is required to suppress polarization effects inside the material to improve the light emitting performance of the device.

However, various properties of the AlGaN-based deep ultraviolet LED epitaxial wafer provided in the prior art need to be improved.

SUMMERY OF THE UTILITY MODEL

The utility model aims at nonpolar AlGaN base deep ultraviolet LED epitaxial wafer aims at solving among the prior art problem that nonpolar AlGaN base deep ultraviolet LED epitaxial wafer performance remains to improve.

The embodiment of the utility model provides a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer, wherein, include: the solar cell comprises a low-temperature AlN layer grown on an r-plane sapphire substrate, a high-temperature AlN layer grown on the low-temperature AlN layer, a non-doped a-plane AlGaN buffer layer grown on the high-temperature AlN layer, an n-type doped a-plane AlGaN layer grown on the non-doped a-plane AlGaN layer, an a-plane AlGaN multi-quantum well layer grown on the n-type doped a-plane AlGaN layer, an electron blocking layer grown on the a-plane AlGaN multi-quantum well layer, and a p-type doped AlGaN thin film grown on the electron blocking layer.

Preferably, the thickness of the low-temperature AlN layer is 5-50 nm.

Preferably, the thickness of the high-temperature AlN layer is 200-500 nm.

Preferably, the thickness of the undoped a-plane AlGaN buffer layer is 500-1000 nm.

Preferably, the thickness of the n-type doped a-plane AlGaN layer is 3-5 μm.

Preferably, the a-plane AlGaN multi-quantum well layer consists of 7-10 periods of Al_0.3Ga_0.7N well layer and Al_0.5Ga_0.5N barrier layers.

Preferably, the Al is_0.3Ga_0.7The thickness of the N well layer is 2-3 nm.

Preferably, the Al is_0.5Ga_0.5The thickness of the N barrier layer is 10-13 nm.

Preferably, the electron blocking layer is Al_0.4Ga_0.6And the thickness of the electron blocking layer is 20-50 nm.

Preferably, the thickness of the p-type doped AlGaN film is 300-350 nm.

The embodiment of the utility model provides a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer, nonpolar AlGaN base deep ultraviolet LED epitaxial wafer includes: grow on the low temperature AlN layer on the r face sapphire substrate, grow high temperature AlN layer on the low temperature AlN layer, grow on non-doping a face AlGaN buffer layer on the high temperature AlN layer, grow n type on the non-doping a face AlGaN layer mixes a face AlGaN layer, grows a face AlGaN multiple quantum well layer on the n type doping a face AlGaN layer, grow and be in electron barrier layer on the a face AlGaN multiple quantum well layer, growth are in p type on the electron barrier layer mixes the AlGaN film, the utility model discloses a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer defect density is low, crystal quality is good, and electricity, optical property are good.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without any creative effort.

Fig. 1 is a schematic structural diagram of a nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a method for manufacturing a nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer according to an embodiment of the present invention;

fig. 3 is an electroluminescence map of a nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be further understood that the term "and/or" as used in the specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

The embodiment of the utility model provides a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer, as shown in FIG. 1, include: a low-temperature AlN layer 102 grown on an r-plane sapphire substrate 101, a high-temperature AlN layer 103 grown on the low-temperature AlN layer 102, a non-doped a-plane AlGaN buffer layer 104 grown on the high-temperature AlN layer 103, an n-type doped a-plane AlGaN layer 105 grown on the non-doped a-plane AlGaN layer 104, an a-plane AlGaN multi-quantum well layer 106 grown on the n-type doped a-plane AlGaN layer 105, an electron blocking layer 107 grown on the a-plane AlGaN multi-quantum well layer 106, and a p-type doped AlGaN thin film 108 grown on the electron blocking layer 107.

The embodiment of the utility model provides a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer, it grows on r face sapphire substrate 101, and defect density is low, crystal quality is good, and electricity, optical property are good. By growing the nonpolar AlGaN material (comprising the undoped a-surface AlGaN buffer layer and the n-type doped a-surface AlGaN layer) and the multi-quantum well active layer on the r-surface sapphire substrate, the polar effect is effectively solved, and the luminous performance of the LED is effectively improved.

In the embodiment of the utility model provides an in, to polarity III nitride material, its growth direction is parallel with the polarization direction of material, has the polarization electric field up to the MV/cm order of magnitude in growth direction. The polarization electric field bends the energy band of the quantum well, which causes the wave functions of electrons and holes at the quantum well to be separated in space, reduces the recombination efficiency of the electrons and the holes, and finally seriously reduces the luminous efficiency of the device, namely the so-called Quantum Confinement Stark Effect (QCSE). And for non-polar III-nitride materials, the direction of the polarizing electric field is perpendicular to the growth direction of the material. The energy band of the non-polar group III nitride material is not bent by the presence of the polarizing electric field and the wave functions of electrons and holes are exactly spatially aligned, i.e., no QCSE is present. By utilizing the characteristic, the problem that the light emitting efficiency of the deep ultraviolet LED is reduced due to QCSE can be solved fundamentally, and the problem that the efficiency of the deep ultraviolet LED is reduced along with the increase of the injection current is relieved to a great extent. On the other hand, due to its own characteristics, nonpolar group III nitride materials are more easily activated when p-type doping is performed than polar materials, and p-type materials with high hole concentration are more easily realized.

The r-plane sapphire substrate 101 may be an ordinary commercial substrate of r-plane orientation.

In one embodiment, the thickness of the low-temperature AlN layer 102 is 5 to 50 nm.

In one embodiment, the thickness of the high temperature AlN layer 103 is 200 to 500 nm.

In one embodiment, the thickness of the undoped a-plane AlGaN buffer layer 104 is 500 to 1000 nm.

In one embodiment, the thickness of the n-type doped a-plane AlGaN layer 105 is 3 to 5 μm. Specifically, the n-type doped a-plane AlGaN layer 105 is doped with Si, and the doping concentration of Si may be 1 × 10¹⁷～1×10²⁰cm^-3. Since AlGaN lattice mismatched with AlN is grown on AlN, there are a large number of defects, and thus a layer of undoped a-plane AlGaN is grown as a buffer layer, and then the n-type doped a-plane AlGaN layer 105 is grown.

In one embodiment, the a-plane AlGaN MQW layer 106 is Al with 7-10 periods_0.3Ga_0.7N well layer and Al_0.5Ga_0.5And N barrier layers. The period here means a layer of Al_0.3Ga_0.7N well layer and one layer of Al_0.5Ga_0.5The N barrier layers are alternately arranged to form a period, and 7-10 periods are arranged in total.

In one embodiment, the Al_0.3Ga_0.7The thickness of the N well layer is 2-3 nm, and the Al is_0.5Ga_0.5The thickness of the N barrier layer is 10-13 nm.

In one embodiment, the electron blocking layer 107 is Al_0.4Ga_0.6And the thickness of the electron blocking layer 107 is 20-50 nm. In order to avoid that the injected electrons can not be radiated and recombined in the active region with high efficiency, the embodiment of the utility model provides an electron blocking layer is provided.

In one embodiment, the thickness of the p-type doped AlGaN film 108 is 300to 350 nm.

The embodiment of the utility model provides a still provide a preparation method of nonpolar AlGaN base deep ultraviolet LED epitaxial wafer as above, as shown in FIG. 2, it includes:

s201, selecting a r-plane sapphire substrate;

s202, forming a low-temperature AlN layer on the r-plane sapphire substrate;

s203, growing a high-temperature AlN layer on the low-temperature AlN layer;

s204, growing a non-doped a-surface AlGaN buffer layer on the high-temperature AlN layer;

s205, growing an n-type doped a-surface AlGaN layer on the undoped a-surface AlGaN buffer layer;

s206, epitaxially growing an a-surface AlGaN multi-quantum well layer on the n-type doped a-surface AlGaN layer;

s207, epitaxially growing an electronic barrier layer on the a-plane AlGaN multi-quantum well layer;

s208, epitaxially growing a p-type doped AlGaN film on the electron barrier layer

In step S202, the r-plane sapphire substrate is subjected to a nitridation process, and then a low-temperature AlN layer is grown. Specifically, a molecular beam epitaxial growth method can be adopted to carry out nitridation on the r-plane sapphire substrate, and the process conditions are as follows: the substrate temperature is 700-900 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the nitridation time is 10-50 minutes; then growing a low-temperature AlN layer on the nitrided r-face sapphire substrate, wherein the process conditions are as follows: the substrate temperature is 500-700 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the temperature of the Al beam source is 1000-1200 ℃.

In step S203, the low-temperature AlN layer is nitrided, and then a high-temperature AlN layer is grown. Specifically, a molecular beam growth method can be adopted, the low-temperature AlN layer is firstly nitrided, and the process conditions are as follows: the substrate temperature is 700-900 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the nitridation time is 10-50 minutes; then growing a high-temperature AlN layer on the nitrided low-temperature AlN layer, wherein the process conditions are as follows: the substrate temperature is 800-1100 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the temperature of the Al beam source is 1000-1200 ℃.

In step S204, the high-temperature AlN layer is nitrided, and then an undoped a-plane AlGaN buffer layer is grown. Specifically, a molecular beam growth method can be adopted, the high-temperature AlN layer is firstly nitrided, and the process conditions are as follows: the substrate temperature is 700-900 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the nitridation time is 10-50 minutes; then growing a nonpolar a-surface AlGaN buffer layer on the nitrided high-temperature AlN layer, wherein the process conditions are as follows: the substrate temperature is 800-1100 ℃, the nitrogen plasma power is 300-450W, the nitrogen flow is 1-5 sccm, and the temperature of the Al beam source is 1000-1200 ℃.

In step S205, the undoped a-plane AlGaN buffer layer is nitrided, and then an n-type doped a-plane AlGaN layer is epitaxially grown. Specifically, an n-type doped a-plane AlGaN layer can be grown on the undoped a-plane AlGaN buffer layer by using a metal organic chemical vapor deposition method, and the process conditions are as follows: the pressure of the reaction chamber is 50-300 torr, the temperature of the substrate is 1000-1260 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 mu m/h; the n-type doped AlGaN layer is doped with Si with the doping concentration of 1 multiplied by 10¹⁷～1×10²⁰cm^-3。

In step S206, an a-plane AlGaN multi-quantum well layer is epitaxially grown on the n-type doped a-plane AlGaN layer. Specifically, a metal organic chemical vapor deposition method can be adopted to grow 7-10 periods of Al on the n-type doped a-surface AlGaN layer_0.3Ga_0.7N well layer/Al_0.5Ga_0.5N base layers, the process conditions are as follows: the pressure in the reaction chamber is 50-300 torr, the substrate temperature is 1000-1260 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 μm/h

In step S207, an electron blocking layer is epitaxially grown on the a-plane AlGaN multi-quantum well layer. Specifically, the metal organic chemical vapor deposition method can be adopted to grow Al on the a-surface AlGaN multi-quantum well layer_0.4Ga_0.6The process conditions of the N electron blocking layer are as follows: the pressure in the reaction chamber is 50-300 torr, the substrate temperature is 1000-1260 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 μm/h.

In step S208, a p-type doped AlGaN thin film is epitaxially grown on the electron blocking layer. Specifically, a metal organic chemical vapor deposition method can be adopted to grow a p-type doped AlGaN film on the electron blocking layer, and the process conditions are as follows: the pressure in the reaction chamber is 50-300 torr, the substrate temperature is 1000-1260 ℃, the beam current ratio V/III is 3000-5000, and the growth rate is 2-4 μm/h.

The nonpolar AlGaN base deep ultraviolet LED epitaxial wafer provided by the embodiment of the utility model has an electroluminescence map as shown in figure 3.

The embodiment of the utility model adopts r-plane sapphire as the substrate of the deep ultraviolet LED, and obtains nonpolar a-plane AlGaN material; the epitaxial structure of the embodiment of the utility model fundamentally eliminates the strong polarization problem existing in c-plane polarity AlGaN-based materials, eliminates the self-polarization in the LED, enables electrons and holes in an active region to be more easily subjected to radiation recombination, improves the quantum efficiency in the deep ultraviolet LED, and improves the luminescence of the deep ultraviolet LED; the deep ultraviolet LED epitaxial wafer provided by the embodiment of the utility model can effectively reduce the formation of dislocation, improve the radiation recombination efficiency of carriers, and can prepare the deep ultraviolet LED with high heat conduction, high electric conduction and high luminous performance; the embodiment of the utility model provides a preparation simple process has the repeatability, can realize large-scale production and application.

The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims

1. The utility model provides a nonpolar AlGaN base deep ultraviolet LED epitaxial wafer which characterized in that includes: the solar cell comprises a low-temperature AlN layer grown on an r-plane sapphire substrate, a high-temperature AlN layer grown on the low-temperature AlN layer, a non-doped a-plane AlGaN buffer layer grown on the high-temperature AlN layer, an n-type doped a-plane AlGaN layer grown on the non-doped a-plane AlGaN layer, an a-plane AlGaN multi-quantum well layer grown on the n-type doped a-plane AlGaN layer, an electron blocking layer grown on the a-plane AlGaN multi-quantum well layer, and a p-type doped AlGaN thin film grown on the electron blocking layer.

2. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the thickness of the low-temperature AlN layer is 5 to 50 nm.

3. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the thickness of the high-temperature AlN layer is 200 to 500 nm.

4. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the thickness of the undoped a-plane AlGaN buffer layer is 500-1000 nm.

5. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the thickness of the n-type doped a-plane AlGaN layer is 3-5 μm.

6. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the a-plane AlGaN multi-quantum well layer consists of 7-10 periods of Al_0.3Ga_0.7N well layer and Al_0.5Ga_0.5N barrier layers.

7. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 6, wherein the Al is_0.3Ga_0.7The thickness of the N well layer is 2-3 nm.

8. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 6, wherein the Al is_0.5Ga_0.5The thickness of the N barrier layer is 10-13 nm.

9. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer according to claim 1, wherein the electron blocking layer is Al_0.4Ga_0.6And the thickness of the electron blocking layer is 20-50 nm.

10. The nonpolar AlGaN-based deep ultraviolet LED epitaxial wafer as claimed in claim 1, wherein the thickness of the p-type doped AlGaN film is 300-350 nm.