Compound substrate for ingan-based optoelectronic devices and method of manufacturing and use thereof

Abstract

The application relates to a composite substrate of an InGaN-based optoelectronic device and a preparation method and application thereof. The composite substrate of the InGaN-based optoelectronic device comprises a crystal base, an AlN transition layer located on the crystal base, the AlN transition layer being composed of a plurality of first three-dimensional growth islands, and a GaN transition layer located on the AlN transition layer, the GaN transition layer being composed of a plurality of second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer being continuations of the plurality of first three-dimensional growth islands in the AlN transition layer. In the composite substrate of the InGaN-based optoelectronic device, the AlN transition layer and the GaN transition layer form a composite transition layer, the stress state in a nitride heteroepitaxial film can be modulated, the incorporation efficiency of In atoms in an InGaN material epitaxial process in the InGaN-based optoelectronic device is improved, and therefore the epitaxial crystal quality of an InGaN film and a quantum structure is improved. In addition, the application also relates to a preparation method of the composite substrate of the InGaN-based optoelectronic device, a template of the InGaN-based optoelectronic device and a preparation method thereof.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic devices, in particular to a composite substrate for InGaN-based optoelectronic devices and a preparation method and application thereof. BACKGROUND

[0002] The wavelength range corresponding to InGaN material extends continuously from the infrared band to the ultraviolet band, and InGaN material has the advantages of direct band gap, high electron mobility, good mechanical and chemical stability, excellent radiation resistance and temperature characteristics, etc., so it has received extensive attention in the field of optoelectronics. In recent years, InGaN material has achieved great success in the fields of solid-state lighting, ultraviolet sterilization, visible light communication and LED display. However, in InGaN-based optoelectronic devices, as the In content gradually increases, the crystal quality of InGaN material decreases sharply, and the application of high-In-content InGaN material is greatly limited.

[0003] It is still very difficult to prepare high-quality high-In-content InGaN material, the main reasons are: 1. Lack of lattice-matched substrate, at present, InGaN material is mainly prepared on GaN substrate or template by epitaxy method, the lattice mismatch between epitaxial layer and substrate not only produces a large number of mismatch dislocations, but also introduces a huge compressive stress in the epitaxial process of InGaN thin film and quantum structure; 2. As the In content increases, the growth temperature of InGaN material gradually decreases, resulting in insufficient ammonia cracking efficiency and insufficient atomic migration distance on the substrate surface, which makes the epitaxial crystal quality of high-In-content InGaN material worse.

[0004] The key to improving the epitaxial crystal quality of InGaN thin film and quantum structure in InGaN-based optoelectronic devices is to improve the In atom incorporation efficiency, and then to increase the epitaxial growth temperature of InGaN material. Theoretical calculations show that when the GaN substrate or template is in a state of weak tensile stress, the incorporation efficiency of In atoms is the highest. A variety of schemes have been proposed internationally to release the compressive stress in GaN heteroepitaxial thin film, such as two-dimensional material transition layer, porous GaN template, InGaN OS template, etc., and experimental results also prove that by releasing the compressive stress existing in GaN thin film, the crystal quality of high-In-content InGaN material is significantly improved. However, these methods are complex, expensive and not completely compatible with existing InGaN material preparation methods, so they are still in the laboratory research stage and still have a distance from practical application. SUMMARY

[0005] Therefore, it is necessary to provide a composite substrate for InGaN-based optoelectronic devices and a preparation method and application thereof in view of the technical problem of how to improve the incorporation efficiency of In content in InGaN-based optoelectronic devices.

[0006] A composite substrate of InGaN-based optoelectronic device, comprising:

[0007] a crystal substrate;

[0008] an AlN transition layer on the crystal substrate, the AlN transition layer being composed of a plurality of first three-dimensional growth islands; and

[0009] a GaN transition layer on the AlN transition layer, the GaN transition layer being composed of a plurality of second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer being continuations of the plurality of first three-dimensional growth islands in the AlN transition layer.

[0010] In the composite substrate of InGaN-based optoelectronic device, the AlN transition layer and the GaN transition layer form a composite transition layer, which can modulate the stress state in the nitride heteroepitaxial film, improve the incorporation efficiency of In atoms in the InGaN material epitaxy process in the InGaN-based optoelectronic device, and thus improve the epitaxial crystal quality of the InGaN film and quantum structure.

[0011] In a feasible implementation, the thickness of the AlN transition layer is 0.5 nm to 500 nm.

[0012] In a feasible implementation, the thickness of the GaN transition layer is 0.5 nm to 500 nm.

[0013] In a feasible implementation, the material of the crystal substrate is sapphire, gallium nitride, silicon, silicon carbide, or gallium oxide.

[0014] A method for preparing a composite substrate of InGaN-based optoelectronic device, comprising the following steps:

[0015] forming an AlN transition layer on a crystal substrate by physical vapor deposition, the AlN transition layer being composed of a plurality of first three-dimensional growth islands;

[0016] epitaxially growing a GaN transition layer on the AlN transition layer, the GaN transition layer being composed of a plurality of second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer being continuations of the plurality of first three-dimensional growth islands in the AlN transition layer, to obtain a composite substrate of InGaN-based optoelectronic device.

[0017] The preparation method of the composite substrate of the InGaN-based optoelectronic device has simple process, and in the preparation process, the AlN transition layer and the GaN transition layer form the composite transition layer, the stress state in the nitride heteroepitaxial film can be modulated, the incorporation efficiency of In atoms in the InGaN material in the epitaxy process of the InGaN-based optoelectronic device is improved, and therefore the epitaxial crystal quality of the InGaN film and the quantum structure is improved.

[0018] In a feasible implementation, the operation of forming the AlN transition layer on the crystal substrate by physical vapor deposition is as follows: a target with a purity of ≥99.99% is used to form the AlN transition layer on the crystal substrate by sputtering in a mixed atmosphere of argon and nitrogen; wherein the working pressure is 0.1 Pa to 1 Pa, the volume fraction of nitrogen in the mixed atmosphere is 10% to 90%, the temperature of the crystal substrate is 20°C to 800°C, and the sputtering power is 1000 W to 5000 W.

[0019] In a feasible implementation, in the operation of epitaxially growing the GaN transition layer on the AlN transition layer, the growth temperature is 500°C to 600°C.

[0020] A preparation method of a template of an InGaN-based optoelectronic device, characterized by comprising the following steps:

[0021] The nitride conversion layer is epitaxially grown on the composite substrate of the InGaN-based optoelectronic device in a two-dimensional epitaxial mode, so that the grain boundaries of the second three-dimensional growth islands in the GaN transition layer are merged, and the tensile stress induced by the grain boundary merging is provided in the nitride conversion layer, to obtain the template of the InGaN-based optoelectronic device.

[0022] In a feasible implementation, in the operation of epitaxially growing the nitride conversion layer, the growth temperature is 600°C to 1200°C.

[0023] In a feasible implementation, the nitride conversion layer is a GaN layer, an AlN layer or an InGaN layer; and / or the thickness of the nitride conversion layer is 0.1 μm to 10 μm.

[0024] A template of an InGaN-based optoelectronic device is prepared by using the preparation method of the template of the InGaN-based optoelectronic device.

[0025] In the template of InGaN-based optoelectronic device and the preparation method thereof, the second three-dimensional growth island grain boundaries in the GaN transition layer can be quickly merged in the process of epitaxially growing the nitride conversion layer, and the tensile stress induced by the grain boundary merging is provided in the continuous epitaxial film (i.e. the nitride conversion layer), so that the stress state in the nitride heteroepitaxial film is modulated, the incorporation efficiency of In atoms in the InGaN material in the epitaxial process of the InGaN-based optoelectronic device is improved, and thus the epitaxial crystal quality of the InGaN thin film and quantum structure is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A schematic diagram of a composite substrate of an InGaN-based optoelectronic device according to an embodiment of the present application;

[0027] Figure 2 A flow chart of a preparation method of a composite substrate of an InGaN-based optoelectronic device according to an embodiment of the present application;

[0028] Figure 3 A schematic diagram of a template of an InGaN-based optoelectronic device according to an embodiment of the present application;

[0029] Figure 4 A schematic diagram of an InGaN-based optoelectronic device according to an embodiment of the present application;

[0030] Figure 5 A schematic diagram of an InGaN-based optoelectronic device of Comparative Example 1;

[0031] Figure 6 A schematic diagram of an InGaN-based optoelectronic device of Comparative Example 2;

[0032] Figure 7 An atomic force microscope image of a GaN transition layer surface of an InGaN-based optoelectronic device of Example 1;

[0033] Figure 8 An atomic force microscope image of an AlN transition layer surface of an InGaN-based optoelectronic device of Comparative Example 1;

[0034] Figure 9 An atomic force microscope image of a GaN transition layer surface of an InGaN-based optoelectronic device of Comparative Example 2;

[0035] Figure 10 Reflectivity recorded in the process of epitaxial growth in steps 5) to 6) of Example 1 and steps 4) to 5) of Comparative Example 1 and Comparative Example 2;

[0036] Figure 11 In-situ monitoring curve of the warpage degree recorded in the process of epitaxial growth in steps 5) to 6) of Example 1 and steps 4) to 5) of Comparative Example 1 and Comparative Example 2;

[0037] Figure 12 Electroluminescence spectra of InGaN-based optoelectronic devices of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0038] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced in a variety of ways beyond the specific embodiments described herein without departing from the spirit of the present application, and that the present application is not limited to the specific embodiments disclosed below.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] Reference will now be made to Figure 1 In one embodiment of the present application, the composite substrate 100 of the InGaN-based optoelectronic device comprises a crystal base 110, an AlN transition layer 120 and a GaN transition layer 130. The crystal base 110 is used to support the AlN transition layer 120 and the GaN transition layer 130 located on the upper layer, and the size and thickness of the crystal base 110 are not limited.

[0041] The crystal base 110 refers to the material of the base being a crystal. The AlN transition layer 120 is located on the crystal base 110, and the AlN transition layer 120 comprises a plurality of first three-dimensional growth islands. Specifically, the AlN transition layer 120 is composed of a large number of dense first three-dimensional growth islands. The AlN transition layer 120 provides an initial growth state and increases the consistency of the grain orientation in a certain direction. In addition, the AlN transition layer 120 can also prevent Ga from corroding the crystal base 110 when the GaN is subsequently grown.

[0042] The GaN transition layer 130 is located on the AlN transition layer 120, and the GaN transition layer 130 comprises a plurality of second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer 130 are respectively located on the plurality of first three-dimensional growth islands in the AlN transition layer 120. Specifically, the GaN transition layer 130 is composed of a large number of dense second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer 130 are the continuation and development of the plurality of first three-dimensional growth islands in the AlN transition layer 120.

[0043] In the above embodiment, the AlN transition layer 120 and the GaN transition layer 130 form a composite transition layer, which can modulate the stress state in the nitride heteroepitaxial film, improve the incorporation efficiency of In atoms in the InGaN material epitaxy process in the InGaN-based optoelectronic device, and thus improve the epitaxial crystal quality of the InGaN film and quantum structure.

[0044] On the basis of the foregoing embodiment, the thickness of the AlN transition layer 120 is 0.5 nm to 500 nm. For example, the thickness of the AlN transition layer 120 can be 0.5 nm, 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm.

[0045] On the basis of the foregoing embodiment, the thickness of the GaN transition layer 130 is 0.5 nm to 500 nm. For example, the thickness of the GaN transition layer 130 can be 0.5 nm, 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm.

[0046] On the basis of the foregoing embodiment, the crystal substrate 110 is selected from at least one of a sapphire substrate, a gallium nitride substrate, an aluminum nitride substrate, a silicon substrate, a silicon carbide substrate, and a gallium oxide substrate. That is, the crystal substrate 110 can be a single-layer sapphire substrate, a single-layer gallium nitride substrate, a single-layer aluminum nitride substrate, a single-layer silicon substrate, a single-layer silicon carbide substrate, or a single-layer gallium oxide substrate, or can be a multi-layer substrate composed of a plurality of substrate layers of the same or different materials.

[0047] In the composite substrate of the InGaN-based optoelectronic device of the present application, the AlN transition layer including a plurality of first three-dimensional growth islands and the GaN transition layer including a plurality of second three-dimensional growth islands form a composite transition layer, which can modulate the stress state in the nitride heteroepitaxial film, improve the incorporation efficiency of In atoms in the InGaN material epitaxy process in the InGaN-based optoelectronic device, and thus improve the epitaxial crystal quality of the InGaN film and quantum structure.

[0048] See Figure 2 The method for preparing the composite substrate 100 of the InGaN-based optoelectronic device according to an embodiment of the present application includes the following steps:

[0049] S10, an AlN transition layer is formed on a crystal substrate by a physical vapor deposition method, and the AlN transition layer is composed of a plurality of first three-dimensional growth islands.

[0050] In step S10, the AlN transition layer 120 formed on the crystal substrate 110 by physical vapor deposition is composed of a large number of dense crystal grains, and the c-axis orientation of the crystal grains has high consistency. The process parameters of thin film deposition and deposition time can be adjusted to control the thickness, surface morphology and crystal quality of the AlN transition layer 120. The AlN transition layer 120 can also be subjected to high-temperature annealing treatment to improve its crystalline quality.

[0051] In one possible implementation, the operation of forming the AlN transition layer 120 on the crystal substrate 110 by physical vapor deposition is as follows: a target material with a purity of ≥99.99% is used to sputter and form an AlN transition layer on the crystal substrate in a mixed atmosphere of argon and nitrogen; the working pressure is 0.1 Pa to 1 Pa, the volume fraction of nitrogen in the mixed atmosphere is 10% to 90%, the temperature of the crystal substrate is 20°C to 800°C, and the sputtering power is 1000 W to 5000 W. The target material can be high-purity aluminum. The argon in the mixed atmosphere is the sputtering gas, which can be high-purity argon, and the nitrogen is the reaction gas, which can be high-purity nitrogen. Specifically, high-purity argon is discharged as ions under the electric field, and then the ions bombard the high-purity aluminum as the sputtering target after being accelerated by the electric field, so that the aluminum atoms of the target are sputtered out and form aluminum nitride with high-purity nitrogen as the reaction gas and deposit on the surface of the heated crystal substrate.

[0052] In step S20, a GaN transition layer is epitaxially grown on the AlN transition layer obtained in step S10, the GaN transition layer is composed of a plurality of second three-dimensional growth islands, and the plurality of second three-dimensional growth islands in the GaN transition layer are continuations of the plurality of first three-dimensional growth islands in the AlN transition layer, thereby obtaining a composite substrate of an InGaN-based optoelectronic device.

[0053] In step S20, the heteroepitaxial substrate coated with the AlN transition layer 120 can be loaded onto the heated base of an epitaxial device to epitaxially prepare a GaN transition layer 130 on the AlN transition layer 120 under appropriate temperature and other process parameters. The prepared GaN transition layer 130 is composed of a large number of second three-dimensional growth islands, and the second three-dimensional growth islands in the GaN transition layer 130 are continuations and developments of the first three-dimensional growth islands of the AlN transition layer 120. By controlling the process conditions and growth time of the GaN transition layer 130, the size and grain boundary density of the second three-dimensional growth islands in the GaN transition layer 130 can be controlled.

[0054] The epitaxial device can be a metal organic chemical vapor deposition (MOCVD), a molecular beam epitaxy (MBE), a hydride vapor phase epitaxy (HVPE) or other forms of epitaxial device. The process conditions include temperature, cavity pressure, V / III ratio, substrate base rotation speed, reaction source flow and other parameters.

[0055] In one possible implementation, the growth temperature is 500-600 DEG C during the epitaxial growth of the GaN transition layer 130 on the AlN transition layer 120. In this case, the formation of the second three-dimensional growth islands and the grain boundaries in the GaN transition layer 130 can be promoted.

[0056] In the InGaN-based optoelectronic device composite substrate 100 prepared by the above steps, the high-quality AlN transition layer 120 is used to reduce the dislocation density in the epitaxial film, and by adjusting the structure of the GaN / AlN composite transition layer and the process conditions of GaN / AlN, the stress regulation and the dislocation density control in the epitaxial film can be simultaneously achieved.

[0057] The preparation method of the InGaN-based optoelectronic device substrate of the present application has a simple process and high compatibility with the existing commercial InGaN-based optoelectronic device epitaxial process, and is easy to be directly applied to large-scale industrial production.

[0058] Referring to Figure 3 The preparation method of the InGaN-based optoelectronic device template 200 of one embodiment of the present application comprises the following steps: growing a nitride conversion layer 210 on the InGaN-based optoelectronic device composite substrate 100 in a two-dimensional epitaxial mode, so that the grain boundaries of the second three-dimensional growth islands in the GaN transition layer 130 are merged, and the tensile stress induced by the grain boundary merging is provided in the nitride conversion layer 210.

[0059] In one possible implementation, the growth temperature is 600-1200 DEG C during the epitaxial growth of the nitride conversion layer. In this step, the stress state in the continuous nitride conversion layer 210 can be monitored in real time by monitoring the warping degree of the InGaN-based optoelectronic device composite substrate 100 in situ.

[0060] In one possible implementation, the nitride conversion layer 210 is a GaN layer, an AlN layer or an InGaN layer.

[0061] In one possible implementation, the thickness of the nitride conversion layer 210 is 0.1-10 μm.

[0062] Referring to Figure 3The template 200 of the InGaN-based optoelectronic device in an embodiment of the present application is prepared by the above-mentioned method for preparing the template of the InGaN-based optoelectronic device. Specifically, the template 200 of the InGaN-based optoelectronic device comprises the composite substrate 100 of the InGaN-based optoelectronic device and the nitride conversion layer 210, and the nitride conversion layer 210 is located on the composite substrate 100 of the InGaN-based optoelectronic device. At this time, the grain boundaries of the first three-dimensional growth islands and the second three-dimensional growth islands in the composite substrate 100 are all merged.

[0063] In the above-mentioned template of the InGaN-based optoelectronic device and the method for preparing the same, the second three-dimensional growth island grain boundaries in the GaN transition layer can be quickly merged in the process of epitaxially growing the nitride conversion layer, and the tensile stress induced by the grain boundary merging is provided in the continuous epitaxial film (i.e. the nitride conversion layer), so as to realize the modulation of the stress state in the nitride heteroepitaxial film, improve the incorporation efficiency of In atoms in the epitaxial process of the InGaN material in the InGaN-based optoelectronic device, and thus improve the epitaxial crystal quality of the InGaN film and the quantum structure.

[0064] With reference to the above-mentioned embodiments, in order to make the technical solutions of the present application more specific, clear and easy to understand, the technical solutions of the present application will be exemplified, but it should be noted that the content to be protected by the present application is not limited to the following Example 1.

[0065] Example 1

[0066] Please refer to Figure 4 The InGaN-based optoelectronic device 300 in Example 1 is an InGaN-based red light emitting diode, and comprises, from bottom to top, the template 200 of the InGaN-based optoelectronic device, an n-type GaN layer 310, an InGaN / GaN multi-quantum well layer 320 and a p-type GaN layer 330. The template 200 of the InGaN-based optoelectronic device comprises, from bottom to top, the composite substrate 100 of the InGaN-based optoelectronic device and the nitride conversion layer 210, wherein the material of the nitride conversion layer 210 is GaN. The composite substrate 100 of the InGaN-based optoelectronic device comprises, from bottom to top, the crystal substrate 110, the AlN transition layer 120 and the GaN transition layer 130, wherein the material of the crystal substrate 110 is a c-plane sapphire.

[0067] The method for preparing the InGaN-based red light emitting diode in Example 1 comprises the following steps:

[0068] 1) High purity argon gas is used as sputtering gas to discharge and form ions, which are accelerated by electric field and bombard high purity aluminum (purity≥99.99%) as sputtering target, so that aluminum atoms are sputtered out and form aluminum nitride with high purity nitrogen gas as reaction gas to deposit on the heated crystal substrate 110, and a 25nm-thick AlN transition layer 120 is obtained. The working pressure in the above process is 0.67Pa, the volume fraction of nitrogen gas is 25%, the temperature of the crystal substrate 110 is 550℃, and the sputtering power is 3000W. The formed AlN transition layer 120 is composed of a large number of dense first three-dimensional growth islands, and the c-axis orientation of the first three-dimensional growth islands has high consistency.

[0069] 2) The crystal substrate 110 coated with the AlN transition layer 120 is ultrasonically cleaned in acetone, alcohol and deionized water for 10 minutes respectively, and then the surface is blown dry with dry nitrogen gas.

[0070] 3) The dry crystal substrate 110 coated with the AlN transition layer 120 is loaded onto the heating pedestal of the MOCVD device, and after being heated to 1080℃, a high-temperature surface thermal cleaning process is carried out in a hydrogen atmosphere for 10 minutes.

[0071] 4) The heating pedestal is cooled to 550℃, and trimethylgallium and ammonia gas are introduced into the reaction chamber to prepare a GaN transition layer 130 composed of second three-dimensional growth islands on the AlN transition layer 120, and a composite substrate 100 of InGaN-based optoelectronic devices is obtained. In this embodiment, the thickness of the GaN transition layer 130 is 5nm.

[0072] 5) The temperature of the heating pedestal is increased to 1075℃, the MOCVD cavity pressure is set to 200torr, the V / III ratio is set to 2500, and the rotation speed of the heating pedestal is set to 1200rpm, and a continuous nitride conversion layer 210 is epitaxially prepared on the GaN / AlN composite transition layer in a two-dimensional epitaxial mode, so that the crystal boundaries in the GaN transition layer 130 are quickly merged, and the tensile stress induced by the crystal boundary merging is provided in the nitride conversion layer 210, and a template 200 of InGaN-based optoelectronic devices is obtained. In this embodiment, the thickness of the nitride conversion layer 210 is 2μm.

[0073] 6) On the basis of step 5), the temperature of the heating pedestal is set to 1060℃, the MOCVD cavity pressure is set to 200torr, the V / III ratio is set to 2500, and the rotation speed of the heating pedestal is set to 1200rpm, and an n-type GaN layer 310 is epitaxially grown as a current injection layer of the first conductivity type of the InGaN-based red light emitting diode. In this embodiment, the thickness of the n-type GaN layer 310 is 2μm.

[0074] 7) Based on step 6), InGaN / GaN multiple quantum well layer 320 is epitaxially grown as the light-emitting active region of the InGaN red light LED in a nitrogen carrier gas atmosphere, with the growth temperature of the InGaN potential well layer being 700℃ and the growth temperature of the GaN potential barrier layer being 800℃, the pressure of the MOCVD cavity being 200 torr, the V / III ratio being 4000, and the rotation speed of the heated susceptor being 1200 rpm; the p-type GaN layer 330 is epitaxially prepared as the current injection layer of the second conduction type of the InGaN-based red light LED, with the temperature of the heated susceptor being 950℃, the pressure of the MOCVD cavity being 200 torr, the V / III ratio being 2500, and the rotation speed of the heated susceptor being 1200 rpm, thereby obtaining the InGaN-based optoelectronic device 300 of Example 1.

[0075] Comparative Example 1

[0076] See Figure 5 The InGaN-based optoelectronic device 100’ of Comparative Example 1 is an InGaN-based red light LED, which comprises, from bottom to top, a sapphire substrate 110’, an AlN transition layer 120’, a GaN conversion layer 130’, an n-type GaN layer 140’, an InGaN / GaN multiple quantum well layer 150’, and a p-type GaN layer 160’, wherein the sapphire substrate 110’ is made of a c-plane sapphire.

[0077] The preparation method of the InGaN-based red light LED of Comparative Example 1 comprises the following steps:

[0078] 1) High-purity argon gas is discharged as an ion to bombard high-purity aluminum (purity ≥ 99.99%) as a sputtering target after acceleration by an electric field, so that the target aluminum atoms are sputtered out to form aluminum nitride with high-purity nitrogen gas as a reaction gas and deposit on the heated sapphire substrate 110’, thereby obtaining an AlN transition layer 120’ with a thickness of 25 nm. The working pressure in the above process is 0.67 Pa, the volume fraction of nitrogen is 25%, the temperature of the sapphire substrate 110’ is 550℃, and the sputtering power is 3000 W. The formed AlN transition layer 120’ is composed of a large number of dense first three-dimensional growth islands, and the c-axis orientation of the first three-dimensional growth islands has high consistency.

[0079] 2) The sapphire substrate 110’ coated with the AlN transition layer 120’ is ultrasonically cleaned in acetone, alcohol, and deionized water for 10 minutes each, and then the surface is blown dry with dry nitrogen.

[0080] 3) The dry sapphire substrate 110’ coated with the AlN transition layer 120’ is loaded onto the heated susceptor of the MOCVD device, and after being heated to 1080℃, a high-temperature surface thermal cleaning process is performed in a hydrogen atmosphere for 10 minutes.

[0081] 4) Adjust the temperature of the heated susceptor to 1075 °C, set the MOCVD chamber pressure to 200 torr, the V / III ratio to 2500 and the rotation speed of the heated susceptor to 1200 rpm, and epitaxially grow a continuous GaN conversion layer 130' on the AlN transition layer in a two-dimensional epitaxial mode. In this comparative example, the thickness of the GaN conversion layer 130' is 2 μm.

[0082] 5) On the basis of step 4), set the temperature of the heated susceptor to 1060 °C, the MOCVD chamber pressure to 200 torr, the V / III ratio to 2500 and the rotation speed of the heated susceptor to 1200 rpm, and epitaxially grow an n-type GaN layer 140' as a current injection layer of the first conductivity type of the InGaN-based red light emitting diode. In this comparative example, the thickness of the n-type GaN layer is 2 μm.

[0083] 6) On the basis of step 5), set the MOCVD chamber pressure to 200 torr, the V / III ratio to 4000 and the rotation speed of the heated susceptor to 1200 rpm, and epitaxially grow an InGaN / GaN multi-quantum well layer 150' as a light emitting active region of the InGaN red light LED in a nitrogen carrier gas atmosphere, wherein the growth temperature of the InGaN potential well layer is 700 °C and the growth temperature of the GaN potential barrier layer is 800 °C; set the temperature of the heated susceptor to 950 °C, the MOCVD chamber pressure to 200 torr, the V / III ratio to 2500 and the rotation speed of the heated susceptor to 1200 rpm, and epitaxially grow a p-type GaN layer 160' as a current injection layer of the second conductivity type of the InGaN-based red light emitting diode, thereby obtaining the InGaN-based optoelectronic device 100' of Comparative Example 1.

[0084] Comparative Example 2

[0085] See Figure 6 The InGaN-based optoelectronic device 200' of Comparative Example 2 is an InGaN-based red light emitting diode, which comprises, from bottom to top, a sapphire substrate 210', a GaN transition layer 220', a GaN conversion layer 230', an n-type GaN layer 240', an InGaN / GaN multi-quantum well layer 250' and a p-type GaN layer 260', wherein the sapphire substrate 210' is made of a c-plane sapphire.

[0086] The method for preparing the InGaN-based red light emitting diode of Comparative Example 2 comprises the following steps:

[0087] 1) Ultrasonically clean the sapphire substrate 210' in acetone, alcohol and deionized water for 10 minutes each, and then blow-dry the surface of the substrate with dry nitrogen.

[0088] 2) The dried sapphire substrate 210' is loaded onto the heating base of the MOCVD equipment, heated to 1080°C, and then subjected to a high-temperature surface thermal cleaning process for 10 minutes in a hydrogen atmosphere.

[0089] 3) Cool the heating base to 550℃, and introduce trimethylgallium and ammonia gas into the reaction chamber, such as... Figure 5 As shown, a GaN transition layer 220' composed of three-dimensionally grown islands is fabricated on a sapphire substrate 210'. In this comparative example, the thickness of the GaN transition layer 220' is 5 nm.

[0090] 4) The temperature of the heating substrate was increased to 1075℃, and the MOCVD chamber pressure was set to 200 torr, the V / III ratio to 2500, and the heating substrate rotation speed to 1200 rpm. A continuous GaN conversion layer 230' was epitaxially prepared on the GaN transition layer 220' using a two-dimensional epitaxial mode. In this comparative example, the thickness of the GaN conversion layer 230' was 2 μm.

[0091] 5) Based on step 4), the temperature of the heating base was set to 1060℃, the MOCVD chamber pressure to 200 torr, the V / III ratio to 2500, and the heating base rotation speed to 1200 rpm. An n-type GaN layer 240' was epitaxially grown as the first conductivity type current injection layer for the InGaN-based red light-emitting diode. In this comparative example, the thickness of the n-type GaN layer 240' was 2 μm.

[0092] 6) Based on step 5), the MOCVD chamber pressure was set to 200 torr, the V / III ratio to 4000, and the heating base rotation speed to 1200 rpm. An InGaN / GaN multi-quantum-well layer 250' was epitaxially grown in a nitrogen carrier gas atmosphere as the light-emitting active region of the InGaN red LED. The growth temperature of the InGaN potential well layer was 700℃, and the growth temperature of the GaN barrier layer was 800℃. The heating base temperature was set to 950℃, the MOCVD chamber pressure to 200 torr, the V / III ratio to 2500, and the heating base rotation speed to 1200 rpm. A p-type GaN layer 260' was epitaxially prepared as the current injection layer of the second conductivity type of the InGaN-based red LED, resulting in the InGaN-based optoelectronic device 200' of Comparative Example 2.

[0093] Performance testing:

[0094] Atomic force microscopy (AFM) scans were performed on the GaN transition layer surface of the InGaN-based optoelectronic device of Example 1, the AlN transition layer surface of the InGaN-based optoelectronic device of Comparative Example 1, and the GaN transition layer surface of the InGaN-based optoelectronic device of Comparative Example 2, respectively, to obtain... Figures 7 to 9 .Depend on Figures 7 to 9It can be seen that the transition layers with different structures have different surface morphology characteristics, the GaN transition layer of the InGaN-based optoelectronic device of Example 1 is composed of second three-dimensional growth islands with large size, the three-dimensional islands are connected with each other and there are cavities between the three-dimensional islands, the AlN transition layer of the InGaN-based optoelectronic device of Comparative Example 1 is composed of three-dimensional growth islands with small size to form a dense quasi-continuous film, and the GaN transition layer of the InGaN-based optoelectronic device of Comparative Example 2 is composed of three-dimensional growth islands with small size and low density.

[0095] The reflectivity and warpage during the epitaxial growth of steps 5) to 6) in Example 1 and steps 4) to 5) in Comparative Examples 1 and 2 are monitored in situ to obtain Figure 10 and Figure 11 It can be seen from Figure 10 and Figure 11 that for the case of using the GaN transition layer in Comparative Example 2, it is impossible to prepare the continuous GaN film described in steps 4 to 5) in Comparative Example 2 in a two-dimensional epitaxial mode. According to the in-situ monitoring curves of the warpage of Example 1 and Comparative Example 1, it can be deduced that the tensile stress in the n-type GaN layer of Example 1 and the n-type GaN layer of Comparative Example 1 is 1.72 GPa and 1.51 GPa, respectively.

[0096] The electroluminescence spectra of the InGaN-based optoelectronic devices of Example 1 and Comparative Example 1 are shown in Figure 12 It can be seen from Figure 12 that the LED epitaxial structure for preparing the InGaN-based optoelectronic device in Example 1 using the GaN / AlN composite transition layer has a longer light-emitting wavelength, i.e. a higher In incorporation efficiency.

[0097] The technical features of the above-described embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered to be within the scope of the present disclosure.

[0098] The above-described embodiments only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A template for an InGaN-based optoelectronic device, characterized in that, It includes a composite substrate and a nitride conversion layer, wherein the nitride conversion layer is located on the composite substrate; The composite substrate includes: Crystal substrate; An AlN transition layer, located on the crystal substrate, wherein the AlN transition layer is composed of a plurality of first three-dimensional growth islands; and A GaN transition layer is located on the AlN transition layer. The GaN transition layer is composed of several second three-dimensional growth islands, and the several second three-dimensional growth islands in the GaN transition layer are a continuation of several first three-dimensional growth islands in the AlN transition layer. The AlN transition layer and the GaN transition layer form a composite transition layer, which is used to modulate the stress state in the nitride heteroepitaxial film, thereby improving the incorporation efficiency of In atoms during the epitaxialization of InGaN material in InGaN-based optoelectronic devices. The template for the InGaN-based optoelectronic device is prepared using the following method: An AlN transition layer is formed on a crystal substrate using physical vapor deposition. The AlN transition layer is composed of several first three-dimensional growth islands. A GaN transition layer is epitaxially grown on the AlN transition layer. The GaN transition layer consists of several second three-dimensional growth islands, and the several second three-dimensional growth islands in the GaN transition layer are a continuation of several first three-dimensional growth islands in the AlN transition layer, thus obtaining a composite substrate for InGaN-based optoelectronic devices. The growth temperature of the GaN transition layer is 500℃~600℃, which is used to promote the formation of second three-dimensional growth islands and grain boundaries in the GaN transition layer. A nitride conversion layer is epitaxially grown in a two-dimensional epitaxial mode on the composite substrate of the InGaN-based optoelectronic device, which causes the grain boundaries of the second three-dimensional growth islands in the GaN transition layer to merge, and provides tensile stress induced by grain boundary merging in the nitride conversion layer to improve the incorporation efficiency of In atoms during the epitaxial growth of InGaN material in the InGaN-based optoelectronic device; the growth temperature of the nitride conversion layer is 600℃~1200℃; thus, a template for the InGaN-based optoelectronic device is obtained.

2. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The thickness of the AlN transition layer is 0.5 nm to 500 nm.

3. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The thickness of the GaN transition layer is 0.5 nm to 500 nm.

4. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The crystal substrate is made of sapphire, gallium nitride, silicon, silicon carbide, or gallium oxide.

5. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The operation of forming an AlN transition layer on a crystal substrate using physical vapor deposition is as follows: using a target material with a purity ≥99.99%, the AlN transition layer is sputtered on the crystal substrate in a mixed atmosphere of argon and nitrogen; wherein the working pressure is 0.1 Pa to 1 Pa, the volume fraction of nitrogen in the mixed atmosphere is 10% to 90%, the temperature of the crystal substrate is 20℃ to 800℃, and the sputtering power is 1000W to 5000W.

6. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The nitride conversion layer is a GaN layer, an AlN layer, or an InGaN layer.

7. The template for the InGaN-based optoelectronic device according to claim 1, characterized in that, The thickness of the nitride conversion layer is 0.1 μm to 10 μm.

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