Ingan-based optoelectronic device and method of manufacturing the same

Abstract

The application relates to an InGaN-based optoelectronic device and a preparation method thereof. The preparation method of the InGaN-based optoelectronic device comprises the following steps: forming an AlN transition layer on a crystal substrate, the AlN transition layer being composed of a plurality of first three-dimensional growth islands; 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 a continuation of the plurality of first three-dimensional growth islands in the AlN transition layer, so as to obtain a composite substrate of the InGaN-based optoelectronic device; epitaxially growing a nitride conversion layer on the composite substrate of the InGaN-based optoelectronic device in a two-dimensional epitaxial mode; and forming other device structure layers of the InGaN-based optoelectronic device on the nitride conversion layer, so as to obtain the InGaN-based optoelectronic device. The above preparation method can improve the incorporation efficiency of In components in the InGaN-based optoelectronic device. In addition, the application also relates to an InGaN-based optoelectronic device prepared by using the above preparation method.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device technology, and in particular to an InGaN-based optoelectronic device and its fabrication method. Background Technology

[0002] InGaN materials offer a continuously tunable wavelength range extending from the infrared to the ultraviolet band. They also possess advantages such as a direct bandgap, high electron mobility, good mechanical and chemical stability, excellent radiation resistance, and superior temperature characteristics, making them a focus of attention in the optoelectronics field. In recent years, InGaN materials have achieved great success in areas such as solid-state lighting, ultraviolet sterilization, visible light communication, and LED displays. However, in InGaN-based optoelectronic devices, the crystal quality of InGaN materials decreases sharply with increasing In content, significantly limiting the application of high-In-content InGaN materials.

[0003] The preparation of high-quality, high-In-content InGaN materials remains extremely difficult, mainly due to the following reasons: First, there is a lack of lattice-matched substrates. Currently, InGaN materials are mainly prepared on GaN substrates or templates via epitaxy. The lattice mismatch between the epitaxial layer and the substrate not only generates a large number of mismatched dislocations but also introduces enormous compressive stress during the epitaxialization of InGaN thin films and quantum structures. Second, as the In content increases, the growth temperature of InGaN materials gradually decreases, resulting in insufficient ammonia cracking efficiency and insufficient atomic migration distance on the substrate surface, which degrades the epitaxial crystal quality of high-In-content InGaN materials.

[0004] The key to improving the epitaxial crystal quality of InGaN thin films and quantum structures in InGaN-based optoelectronic devices lies in increasing the induction efficiency of In atoms, thereby raising the epitaxial growth temperature of InGaN materials. Theoretical calculations show that the induction efficiency of In atoms is highest when the GaN substrate or template is under weak tensile stress. Internationally, various schemes have been proposed to release the compressive stress in GaN heteroepitaxial films, such as two-dimensional material transition layers, porous GaN templates, and InGaNOS templates. Experimental results have also demonstrated that releasing the compressive stress in GaN thin films significantly improves the crystal quality of high-In-content InGaN materials. However, these methods are complex, expensive, and not fully compatible with existing InGaN material preparation methods, thus remaining in the laboratory research stage and still some distance from practical application. Summary of the Invention

[0005] Therefore, it is necessary to provide an InGaN-based optoelectronic device and its fabrication method to address the technical problem of how to improve the incorporation efficiency of the In component in InGaN-based optoelectronic devices.

[0006] A method for fabricating an InGaN-based optoelectronic device includes the following steps:

[0007] 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.

[0008] A GaN transition layer is epitaxially grown 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, thus obtaining a composite substrate for InGaN-based optoelectronic devices.

[0009] 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 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; and

[0010] Other device structure layers of the InGaN-based optoelectronic device are formed on the nitride conversion layer to obtain the InGaN-based optoelectronic device.

[0011] The fabrication method of the aforementioned InGaN-based optoelectronic device is simple. During the fabrication process, the AlN transition layer and the GaN transition layer form a composite transition layer, which can modulate the stress state in the nitride conversion layer and improve the incorporation efficiency of In atoms during the epitaxialization of InGaN material in the InGaN-based optoelectronic device, thereby improving the epitaxial crystal quality of the InGaN thin film and quantum structure. The fabrication method of the InGaN-based optoelectronic device of the present invention has high compatibility with the existing commercial InGaN-based optoelectronic device epitaxial process, and can be easily applied directly to large-scale industrial production.

[0012] In one feasible implementation, 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.

[0013] In one feasible implementation, the growth temperature is 500℃~600℃ during the epitaxial growth of the GaN transition layer on the AlN transition layer.

[0014] In one feasible implementation, the growth temperature is 600℃~1200℃ during the operation of epitaxially growing a nitride conversion layer on the composite substrate of the InGaN-based optoelectronic device in a two-dimensional epitaxial mode.

[0015] In one feasible implementation, the thickness of the AlN transition layer is 0.5 nm to 500 nm.

[0016] In one feasible implementation, the thickness of the GaN transition layer is 0.5 nm to 500 nm.

[0017] In one feasible implementation, the crystal substrate is selected from at least one of sapphire substrate, gallium nitride substrate, aluminum nitride substrate, silicon substrate, silicon carbide substrate, and gallium oxide substrate.

[0018] In one feasible implementation, the nitride conversion layer is a GaN layer, an AlN layer, an AlGaN layer, or an InGaN layer; and / or the thickness of the nitride conversion layer is 0.1 μm to 10 μm.

[0019] An InGaN-based optoelectronic device is prepared using any of the above-mentioned methods for preparing InGaN-based optoelectronic devices.

[0020] In the InGaN-based optoelectronic device of the present invention, the incorporation efficiency of In atoms during the epitaxial process of InGaN material is relatively high, thereby improving the epitaxial crystal quality of InGaN thin film and quantum structure, resulting in higher overall efficiency of InGaN-based optoelectronic device.

[0021] In one feasible implementation, the InGaN-based optoelectronic device is an InGaN-based LED, an InGaN-based solar cell, or an InGaN-based laser. Attached Figure Description

[0022] Figure 1 This is a flowchart of a method for fabricating an InGaN-based optoelectronic device according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of a composite substrate for an InGaN-based optoelectronic device according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of a template for an InGaN-based optoelectronic device according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of an InGaN-based optoelectronic device according to an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the InGaN-based optoelectronic device in Comparative Example 1.

[0027] Figure 6 This is a schematic diagram of the InGaN-based optoelectronic device in Comparative Example 2.

[0028] Figure 7 This is an atomic force microscope image of the GaN transition layer surface of the InGaN-based optoelectronic device in Example 1;

[0029] Figure 8 This is an atomic force microscope image of the AlN transition layer surface of the InGaN-based optoelectronic device in Comparative Example 1.

[0030] Figure 9 This is an atomic force microscope image of the GaN transition layer surface of the InGaN-based optoelectronic device in Comparative Example 2.

[0031] Figure 10 These are the reflectances recorded during the epitaxial growth process in steps 5) to 6) of Example 1 and steps 4) to 5) of Comparative Examples 1 and 2;

[0032] Figure 11 These are the in-situ warpage monitoring curves recorded during the epitaxial growth process in steps 5) to 6) of Example 1 and steps 4) to 5) of Comparative Examples 1 and 2;

[0033] Figure 12 These are the electroluminescence spectra of the InGaN-based optoelectronic devices of Example 1 and Comparative Example 1. Detailed Implementation

[0034] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Please see Figure 1 The method for fabricating an InGaN-based optoelectronic device according to an embodiment of the present invention includes the following steps:

[0037] S1. An AlN transition layer is formed on a crystal substrate using physical vapor deposition. The AlN transition layer consists of several first three-dimensional growth islands.

[0038] Please see also Figure 2 In step S1, the crystal substrate 110 refers to a substrate made of crystal, and the crystal substrate 110 is used to support the other layers located on the upper layer.

[0039] In one feasible implementation, the crystal substrate 110 is selected from at least one of sapphire substrate, gallium nitride substrate, aluminum nitride substrate, silicon substrate, silicon carbide substrate, and gallium oxide substrate. That is, the crystal substrate 110 can be a single-layer sapphire substrate, gallium nitride substrate, aluminum nitride substrate, silicon substrate, silicon carbide substrate, or gallium oxide substrate, or it can be a multilayer substrate composed of multiple substrates of the same or different materials stacked together.

[0040] In step S1, the AlN transition layer 120 formed on the crystal substrate 110 using physical vapor deposition consists of a large number of dense grains (i.e., first three-dimensional growth islands), and the c-axis orientation of the grains is highly consistent. The AlN transition layer 120 provides the initial growth state and increases the consistency of grain orientation along a certain direction. Furthermore, the AlN transition layer 120 can prevent Ga from corroding the crystal substrate 110 during subsequent GaN growth. The thickness, surface morphology, and crystal quality of the AlN transition layer can be controlled by adjusting the thin film deposition process parameters and deposition time. High-temperature annealing can also be performed on the AlN transition layer to improve its crystallinity.

[0041] In one feasible implementation, the process of forming an AlN transition layer 120 on a crystal substrate 110 using physical vapor deposition involves: using a target material with a purity ≥99.99%, sputtering the AlN transition layer onto 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. 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 reactant gas, which can be high-purity nitrogen. Specifically, high-purity argon is used as the sputtering gas to generate ions through discharge, which, after being accelerated by an electric field, bombard the high-purity aluminum as the sputtering target, causing aluminum atoms from the target to be sputtered and react with the high-purity nitrogen as the reactant gas to form aluminum nitride deposited on the heated crystal substrate surface.

[0042] In one feasible implementation, 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.

[0043] S2. An epitaxial GaN transition layer is grown 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 the several first three-dimensional growth islands in the AlN transition layer, thus obtaining a composite substrate for InGaN-based optoelectronic devices.

[0044] Please see also Figure 2 In step S2, the heteroepitaxial substrate coated with AlN transition layer 120 can be loaded onto the heating base of the epitaxial equipment. Under appropriate temperature and other process parameters, GaN transition layer 130 is epitaxially prepared on AlN transition layer 120. By controlling the process conditions and growth time of GaN transition layer 130, the size and grain boundary density of the second three-dimensional growth island in GaN transition layer 130 can be controlled.

[0045] The epitaxial equipment can be metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), or other forms of epitaxial equipment. The process conditions include parameters such as temperature, chamber pressure, V / III ratio, substrate pedestal rotation speed, and reaction source flow rate.

[0046] In one feasible implementation, the growth temperature of the GaN transition layer 130 epitaxially grown on the AlN transition layer 120 is 500℃ to 600℃. This temperature promotes the formation of second three-dimensional growth islands and grain boundaries in the GaN transition layer 130.

[0047] In one feasible implementation, 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.

[0048] After step S2, we can obtain the following: Figure 2 The composite substrate 100 of the InGaN-based optoelectronic device shown.

[0049] S3. A nitride conversion layer is epitaxially grown on the composite substrate of InGaN-based optoelectronic devices in a two-dimensional epitaxial mode, 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.

[0050] Please see also Figure 3 In step S3, during the epitaxial growth of the nitride conversion layer 210 on the composite substrate 100 of the InGaN-based optoelectronic device in a two-dimensional epitaxial mode, the grain boundaries of the AlN transition layer 120 and the second three-dimensional growth islands in the GaN transition layer 130 can be rapidly merged. Simultaneously, tensile stress induced by grain boundary merging is provided in the continuous epitaxial film (i.e., the nitride conversion layer), thereby modulating the stress state in the nitride heteroepitaxial film.

[0051] In one feasible implementation, the epitaxial growth temperature of the nitride conversion layer 210 is 600℃ to 1200℃. In this step, the stress state in the continuous nitride conversion layer 210 can be monitored in real time by in-situ monitoring of the warpage of the composite substrate 100 of the InGaN-based optoelectronic device.

[0052] In one feasible implementation, the thickness of the nitride conversion layer 210 is 0.1 μm to 10 μm.

[0053] After step S3, we can obtain the following: Figure 3 The template 200 for the InGaN-based optoelectronic device is shown. The template 200 for the InGaN-based optoelectronic device includes, from bottom to top, a composite substrate 100 for the InGaN-based optoelectronic device and a nitride conversion layer 210. The composite substrate 100 for the InGaN-based optoelectronic device includes, from bottom to top, a crystal substrate 110, an AlN transition layer 120 and a GaN transition layer 130.

[0054] S4. Other device structure layers of InGaN-based optoelectronic devices are formed on the nitride conversion layer to obtain InGaN-based optoelectronic devices.

[0055] In step S4, other device structure layers can be formed on the nitride conversion layer using processes commonly used in the art, and the other device structure layers can be selected according to the specific InGaN-based optoelectronic device.

[0056] Please see also Figure 4 In one feasible implementation, the InGaN-based optoelectronic device 300 is an InGaN-based red LED, and the other device structure layers of the InGaN-based optoelectronic device include an n-type GaN layer 310, an InGaN / GaN multi-quantum-well layer 320, and a p-type GaN layer 330.

[0057] The fabrication method of the aforementioned InGaN-based optoelectronic device is simple. During the fabrication process, the AlN transition layer and the GaN transition layer form a composite transition layer, which can modulate the stress state in the nitride conversion layer and improve the incorporation efficiency of In atoms during the epitaxialization of InGaN material in the InGaN-based optoelectronic device, thereby improving the epitaxial crystal quality of the InGaN thin film and quantum structure. The fabrication method of the InGaN-based optoelectronic device of the present invention has high compatibility with the existing commercial InGaN-based optoelectronic device epitaxial process, and can be easily applied directly to large-scale industrial production.

[0058] Please see Figure 4 The InGaN-based optoelectronic device 300 of one embodiment of the present invention is prepared by any of the above-described methods for preparing InGaN-based optoelectronic devices.

[0059] In one feasible implementation, the InGaN-based optoelectronic device 300 is an InGaN-based red LED, comprising, from bottom to top, a template 200, an n-type GaN layer 310, an InGaN / GaN multiple quantum well layer 320, and a p-type GaN layer 330. The template 200, from bottom to top, comprises a composite substrate 100 and a nitride conversion layer 210. The composite substrate 100, from bottom to top, comprises a crystal substrate 110, an AlN transition layer 120, and a GaN transition layer 130.

[0060] Of course, the InGaN-based optoelectronic devices of the present invention are not limited to the InGaN-based LEDs described above, but can also be InGaN-based solar cells or InGaN-based lasers.

[0061] Furthermore, the InGaN-based optoelectronic device 300 of the present invention includes a high-In-content InGaN thin film, a quantum structure, and related auxiliary structures, wherein the high-In-content InGaN thin film, the quantum structure, and related auxiliary structures can be the active region structure of optoelectronic devices such as current injection layers, long-wavelength InGaN-based LEDs, InGaN-based solar cells, and long-wavelength InGaN-based lasers, or other forms of auxiliary structures.

[0062] In the InGaN-based optoelectronic device of the present invention, the incorporation efficiency of In atoms during the epitaxial process of InGaN material is relatively high, thereby improving the epitaxial crystal quality of InGaN thin film and quantum structure, resulting in higher overall efficiency of InGaN-based optoelectronic device.

[0063] Referring to the above implementation details, in order to make the technical solution of this application more specific, clear and easy to understand, examples of the technical solution of this application are given below. However, it should be noted that the content to be protected by this application is not limited to the following embodiment 1.

[0064] Example 1

[0065] Please see Figure 4 The InGaN-based optoelectronic device 300 in Example 1 is an InGaN-based red light-emitting diode, which, from bottom to top, includes a template 200, an n-type GaN layer 310, an InGaN / GaN multiple quantum well layer 320, and a p-type GaN layer 330. The template 200, from bottom to top, includes a composite substrate 100 and a nitride conversion layer 210, wherein the nitride conversion layer 210 is made of GaN. The composite substrate 100, from bottom to top, includes a crystal substrate 110, an AlN transition layer 120, and a GaN transition layer 130, wherein the crystal substrate 110 is made of c-plane sapphire.

[0066] The fabrication method of the InGaN-based red light-emitting diode in Example 1 includes the following steps:

[0067] 1) High-purity argon gas is used as the sputtering gas to generate ions through discharge. After being accelerated by an electric field, these ions bombard high-purity aluminum (purity ≥ 99.99%) as the sputtering target, causing aluminum atoms to be sputtered out and react with high-purity nitrogen gas as the reaction gas to form aluminum nitride, which is deposited on a heated crystal substrate 110, resulting in an AlN transition layer 120 with a thickness of 25 nm. The working pressure in the above process is 0.67 Pa, the nitrogen volume fraction is 25%, the temperature of the crystal substrate 110 is 550 °C, and the sputtering power is 3000 W. The formed AlN transition layer 120 consists of a large number of dense first three-dimensional growth islands, and the c-axis orientation of the first three-dimensional growth islands has a high degree of consistency.

[0068] 2) After ultrasonically cleaning the crystal substrate 110 coated with AlN transition layer 120 for 10 min each in acetone, alcohol and deionized water, the surface was dried with dry nitrogen gas.

[0069] 3) The dried crystal substrate 110 coated with AlN transition layer 120 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.

[0070] 4) The heating base is cooled to 550°C, 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, thus obtaining the composite substrate 100 for InGaN-based optoelectronic devices. In this embodiment, the thickness of the GaN transition layer 130 is 5 nm.

[0071] 5) The temperature of the heating base is raised to 1075℃, and the MOCVD chamber pressure is set to 200 torr, the V / III ratio to 2500, and the heating base rotation speed to 1200 rpm. A continuous nitride conversion layer 210 is epitaxially prepared on the GaN / AlN composite transition layer in a two-dimensional epitaxial mode. This allows the grain boundaries in the GaN transition layer 130 to merge rapidly, providing tensile stress induced by grain boundary merging in the nitride conversion layer 210, thus obtaining the template 200 for the InGaN-based optoelectronic device. In this embodiment, the thickness of the nitride conversion layer 210 is 2 μm.

[0072] 6) Based on step 5), the temperature of the heating base is 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 310 is epitaxially grown as the first conductivity type current injection layer for the InGaN-based red light-emitting diode. In this embodiment, the thickness of the n-type GaN layer 310 is 2 μm.

[0073] 7) Based on step 6), 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 320 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 330 was epitaxially prepared as the current injection layer of the second conductivity type of the InGaN-based red LED, thus obtaining the InGaN-based optoelectronic device 300 of Example 1.

[0074] Comparative Example 1

[0075] Please see Figure 5The InGaN-based optoelectronic device 100' of Comparative Example 1 is an InGaN-based red light-emitting diode, which includes, 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 multi-quantum-well layer 150', and a p-type GaN layer 160'. The sapphire substrate 110' is made of c-plane sapphire.

[0076] The fabrication method of the InGaN-based red light-emitting diode in Comparative Example 1 includes the following steps:

[0077] 1) High-purity argon gas is used as the sputtering gas to generate ions through discharge. After being accelerated by an electric field, these ions bombard high-purity aluminum (purity ≥ 99.99%) as the sputtering target, causing aluminum atoms to be sputtered out and react with high-purity nitrogen gas as the reaction gas to form aluminum nitride, which is deposited on a heated sapphire substrate 110', resulting in an AlN transition layer 120' with a thickness of 25 nm. The working pressure in the above process is 0.67 Pa, the nitrogen volume fraction is 25%, the temperature of the sapphire substrate 110' is 550 °C, and the sputtering power is 3000 W. The formed AlN transition layer 120' consists of a large number of dense first three-dimensional growth islands, and the c-axis orientation of the first three-dimensional growth islands has a high degree of consistency.

[0078] 2) After ultrasonically cleaning the sapphire substrate 110' with AlN transition layer 120' for 10 min each in acetone, alcohol and deionized water, the surface was dried with dry nitrogen gas.

[0079] 3) The dried sapphire substrate 110' coated with the AlN transition layer 120' 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.

[0080] 4) The temperature of the heating base was adjusted to 1075℃, and the MOCVD chamber pressure was set to 200 torr, the V / III ratio to 2500, and the heating base rotation speed to 1200 rpm. A continuous GaN conversion layer 130' was epitaxially prepared on the AlN transition layer using a two-dimensional epitaxial mode. In this comparative example, the thickness of the GaN conversion layer 130' was 2 μm.

[0081] 5) Based on step 4), the temperature of the heating base is 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. The n-type GaN layer 140' is used as the current injection layer of the first conductivity type for the InGaN-based red light-emitting diode. In this comparative example, the thickness of the n-type GaN layer is 2 μm.

[0082] 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 150' 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 160' 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 100' of Comparative Example 1.

[0083] Comparative Example 2

[0084] Please see Figure 6 Comparative Example 2 shows that the InGaN-based optoelectronic device 200' is an InGaN-based red light-emitting diode, which includes, 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'. The sapphire substrate 210' is made of c-plane sapphire.

[0085] The fabrication method of the InGaN-based red light-emitting diode in Comparative Example 2 includes the following steps:

[0086] 1) After ultrasonically cleaning the sapphire substrate 210' in acetone, alcohol and deionized water for 10 minutes each, blow dry the substrate surface with dry nitrogen gas.

[0087] 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.

[0088] 3) Cool the heating base to 550℃, and introduce trimethylgallium and ammonia gas into the reaction chamber, such as... Figure 2 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] Performance testing:

[0093] 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 7-9 .Depend on Figures 7-9 It 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 in Example 1 is composed of large second three-dimensional growth islands, which are connected to each other and have voids. In contrast, the AlN transition layer of the InGaN-based optoelectronic device in Comparative Example 1 is composed of small three-dimensional growth islands forming a dense quasi-continuous film. The GaN transition layer of the InGaN-based optoelectronic device in Comparative Example 2 is composed of small and low-density three-dimensional growth islands.

[0094] In-situ monitoring was performed on the reflectivity and warpage during the epitaxial growth process in steps 5) to 6) of Example 1 and steps 4) to 5) of Comparative Examples 1 and 2 to obtain... Figure 10 and Figure 11 .Depend on Figure 10 and Figure 11It can be seen that, for the case of using a GaN transition layer in Comparative Example 2, it is impossible to prepare the continuous GaN thin film described in steps 4-5) of Comparative Example 2 using a two-dimensional epitaxial mode. Based on the in-situ warpage monitoring curves of Example 1 and Comparative Example 1, the tensile stresses in the n-type GaN layer of Example 1 and the n-type GaN layer of Comparative Example 1 can be calculated to be 1.72 GPa and 1.51 GPa, respectively.

[0095] The electroluminescence spectra of the InGaN-based optoelectronic devices of Example 1 and Comparative Example 1 are as follows: Figure 12 As shown. From Figure 12 It can be seen that the LED epitaxial structure of the InGaN-based optoelectronic device prepared in Example 1 using the GaN / AlN composite transition layer has a longer emission wavelength, i.e., a higher In component incorporation efficiency.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for fabricating an InGaN-based optoelectronic device, characterized in that, The method comprises the following steps: 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; 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 an InGaN-based optoelectronic device; the GaN transition layer has a growth temperature of 500-600°C, for promoting the formation of second three-dimensional growth islands and grain boundaries in the GaN transition layer; epitaxially growing a nitride conversion layer 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 a tensile stress induced by the merging of the grain boundaries is provided in the nitride conversion layer, for improving the incorporation efficiency of In atoms in the epitaxial process of InGaN material in the InGaN-based optoelectronic device; the nitride conversion layer has a growth temperature of 600-1200°C; and forming other device structure layers of the InGaN-based optoelectronic device on the nitride conversion layer, to obtain the InGaN-based optoelectronic device.

2. The method of claim 1, wherein the InGaN-based optoelectronic device is a light emitting diode. The operation of forming the AlN transition layer on the crystal substrate by physical vapor deposition is as follows: using a target material with a purity of ≥99.99%, an AlN transition layer is formed on a crystal substrate by sputtering in a mixed atmosphere of argon and nitrogen; wherein the working gas pressure is 0.1-1 Pa, the volume fraction of nitrogen in the mixed atmosphere is 10-90%, the temperature of the crystal substrate is 20-800°C, and the sputtering power is 1000-5000 W.

3. The method of claim 1, wherein the InGaN-based optoelectronic device is a light emitting diode. The thickness of the AlN transition layer is 0.5-500 nm.

4. The method of claim 1, wherein the InGaN-based optoelectronic device is a light emitting diode. The thickness of the GaN transition layer is 0.5-500 nm.

5. The method of claim 1, wherein the InGaN-based optoelectronic device is a light emitting diode. The crystal substrate 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.

6. The method of fabricating an InGaN-based optoelectronic device of claim 1, wherein, The nitride epitaxial layer is a GaN layer, an AlN layer, an AlGaN layer, or an InGaN layer; and / or the thickness of the nitride epitaxial layer is 0.1-10 μm.

7. An InGaN-based optoelectronic device, characterized by The InGaN-based optoelectronic device is prepared by the method of any one of claims 1-6.

8. The InGaN-based optoelectronic device of claim 7, wherein, The InGaN-based optoelectronic device is an InGaN-based LED, an InGaN-based solar cell, or an InGaN-based laser.

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