Aluminum gallium nitride material and preparation method thereof

Abstract

The invention provides a preparation method of an aluminum gallium nitride material, which can be applied to the technical field of semiconductor photoelectric materials. The method comprises the following steps: growing an aluminum nitride buffer layer on a sapphire substrate; growing an aluminum nitride epitaxial layer on the aluminum nitride buffer layer; growing a superlattice layer on the aluminum nitride epitaxial layer, wherein the superlattice layer comprises an aluminum nitride sub-layer and an aluminum gallium nitride sub-layer which are periodically arranged; growing an aluminum gallium nitride layer on the superlattice layer; the pressure intensity for growing the aluminum nitride buffer layer on the sapphire substrate does not exceed 50 mbar. By setting the nucleation pressure intensity of the aluminum nitride buffer layer, the migration ability and growth mode of aluminum atoms and nitrogen atoms are regulated and controlled, and the trapezoidal defect on the surface of the high-aluminum-component n-type aluminum gallium nitride material is inhibited. The invention also provides an aluminum gallium nitride material.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic materials, and in particular to an aluminum gallium nitride material and a preparation method thereof. Background Art

[0002] High aluminum (Al) component aluminum gallium nitride (AlGaN) material is one of the most promising nitride materials for making deep ultraviolet lasers, deep ultraviolet LEDs, solar-blind detectors and high electron mobility crystals due to its advantages such as direct band gap, high short-wave photon emission and detection efficiency, high electron mobility and high thermal conductivity. High Al component AlGaN material plays an irreplaceable role as part of the PN junction in the core area of ​​the device, and the surface quality of AlGaN material directly affects the performance of the device.

[0003] However, due to the lack of suitable substrates and the low mobility of Al atoms, AlGaN materials have many defects inside and on the surface, which seriously weakens the performance of optoelectronic devices and introduces additional leakage current, resulting in serious degradation of the performance of electronic devices. Therefore, reducing the defects of AlGaN materials and obtaining a smooth and flat surface is of great research significance. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In order to solve at least one of the above-mentioned technical problems of aluminum gallium nitride materials in the prior art, an embodiment of the present invention provides an aluminum gallium nitride material and a preparation method thereof, which suppresses the trapezoidal defects on the surface of high-aluminum component n-type aluminum gallium nitride materials by changing the nucleation pressure of the aluminum nitride buffer layer and regulating the migration ability and growth mode of aluminum atoms and nitrogen.

[0006] (II) Technical solution

[0007] In view of the above technical problems, an embodiment of the present invention provides an aluminum gallium nitride material and a preparation method thereof.

[0008] According to a first aspect of the present invention, a method for preparing an aluminum gallium nitride material is provided, comprising: growing an aluminum nitride buffer layer on a sapphire substrate; growing an aluminum nitride epitaxial layer on the aluminum nitride buffer layer; growing a superlattice layer on the aluminum nitride epitaxial layer, the superlattice layer comprising periodically arranged aluminum nitride sublayers and aluminum gallium nitride sublayers; growing an aluminum gallium nitride layer on the superlattice layer; and stripping to obtain the aluminum gallium nitride material, wherein the pressure at which the aluminum nitride buffer layer is grown on the sapphire substrate does not exceed 50 mbar.

[0009] In some exemplary embodiments, growing an aluminum nitride buffer layer on a sapphire substrate specifically includes: growing the aluminum nitride buffer layer using a metal organic chemical deposition method according to first process parameters, the first process parameters including at least one of the following items: a growth temperature of 1120°C ± 10°C; a growth time of 1300s ± 50s; a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 1670 ± 20.

[0010] In some exemplary embodiments, growing an aluminum nitride epitaxial layer on an aluminum nitride buffer layer specifically includes: growing an aluminum nitride epitaxial layer using a metal organic chemical deposition method according to second process parameters, the second process parameters including at least one of the following items: a growth temperature of 1140°C ± 10°C; a growth time of 5500s ± 50s; a pressure of 50mbar ± 5mbar; and a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 72 ± 2.

[0011] In some exemplary embodiments, growing a superlattice layer on an aluminum nitride epitaxial layer specifically includes: growing a superlattice layer using a metal organic chemical deposition method according to a third process parameter, wherein the third process parameter includes at least one of the following items: a growth temperature of 1120°C ± 10°C; a growth time of 4500s ± 50s; and a pressure of 100mbar ± 5mbar.

[0012] In some exemplary embodiments, growing an aluminum gallium nitride layer on a superlattice layer specifically includes: growing an aluminum gallium nitride layer using a metal organic chemical deposition method according to a fourth process parameter, the fourth process parameter including at least one of the following items: a growth temperature of 1070°C ± 10°C; a growth time of 3000s ± 50s; a pressure of 100mbar ± 5mbar; and a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 850 ± 10.

[0013] In some exemplary embodiments, the precursor material of the nitrogen element in the aluminum nitride buffer layer, the aluminum nitride epitaxial layer, the aluminum nitride sublayer, the aluminum gallium nitride sublayer, and the aluminum gallium nitride layer includes ammonia; and / or the precursor material of the aluminum element in the aluminum nitride buffer layer, the aluminum nitride epitaxial layer, the aluminum nitride sublayer, the aluminum gallium nitride sublayer, and the aluminum gallium nitride layer includes trimethylaluminum.

[0014] In some exemplary embodiments, the precursor material of the gallium element in the AlGaN sub-layer and the AlGaN layer includes trimethylgallium.

[0015] In some exemplary embodiments, the number of periods of the superlattice layer is 100±5; and / or the molar percentage of aluminum element in the superlattice layer is 76%±2%.

[0016] In some exemplary embodiments, the molar percentage of aluminum element in the aluminum gallium nitride layer is 57%±2%.

[0017] According to a second aspect of the present invention, an aluminum gallium nitride material is provided. The aluminum gallium nitride material is prepared by the above method.

[0018] (III) Beneficial effects

[0019] It can be seen from the above technical solutions that an aluminum gallium nitride material and a preparation method and application thereof provided in an embodiment of the present invention have at least the following beneficial effects:

[0020] (1) By changing the nucleation pressure of the aluminum nitride buffer layer, the migration ability and growth mode of aluminum atoms and nitrogen are regulated, and the merging of the aluminum nitride epitaxial layer is promoted, thereby suppressing the V-shaped pits in the aluminum nitride epitaxial layer and the trapezoidal defects on the surface of the subsequent AlGaN material.

[0021] (2) This preparation method is simple to operate, practical and highly repeatable, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram of a process for preparing an aluminum gallium nitride material according to an embodiment of the present invention is shown;

[0024] Figure 2 A schematic diagram of the structure after an aluminum gallium nitride layer is grown on a superlattice layer according to an embodiment of the present invention is shown;

[0025] Figure 3 Schematically showing a scan of an aluminum gallium nitride material obtained when the preparation pressure of the aluminum nitride buffer layer according to an embodiment of the present invention is 80 mar; and

[0026] Figure 4 The schematic diagram shows a scanning image of the aluminum gallium nitride material obtained when the preparation pressure of the aluminum nitride buffer layer according to an embodiment of the present invention is 50 mar.

[0027] Reference numerals:

[0028] 1-sapphire substrate; 2-aluminum nitride buffer layer; 3-aluminum nitride epitaxial layer; 4-superlattice layer; 5-aluminum gallium nitride layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Figure 1 The figure schematically shows a flow chart of a method for preparing an aluminum gallium nitride material according to an embodiment of the present invention.

[0031] like Figure 1 As shown, a method for preparing an aluminum gallium nitride material according to an embodiment of the present invention includes steps S110-S150.

[0032] In step S110, an aluminum nitride buffer layer 2 is grown on the sapphire substrate 1, wherein the pressure for growing the aluminum nitride buffer layer 2 does not exceed 50 mbar.

[0033] In some exemplary embodiments, growing an aluminum nitride buffer layer 2 on a sapphire substrate 1 specifically includes: growing the aluminum nitride buffer layer 2 by a metal organic chemical deposition method according to first process parameters, the first process parameters including at least one of the following items: a growth temperature of 1120°C ± 10°C; a growth time of 1300s ± 50s; a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 1670 ± 20.

[0034] The aluminum nitride material grown at low temperature (1150°C) using the Metal Organic Chemical Vapor Deposition (MOCVD) method has a weak mobility of aluminum atoms. The study found that the nucleation pressure of the aluminum nitride buffer layer 2 has a significant regulatory effect on the mobility of aluminum atoms. High pressure will further inhibit the mobility of aluminum atoms, and the aluminum nitride nucleation layer will form a small, dense, and poorly oriented island structure, making it difficult to merge the subsequent aluminum nitride epitaxial layer 3. Under lower pressure, the mobility of aluminum atoms is improved, which is conducive to the formation of large and dispersed aluminum nitride island structures, and then conducive to the transition from three-dimensional to two-dimensional mode during the growth of the subsequent aluminum nitride epitaxial layer 3, thereby inhibiting the V-shaped pits in the aluminum nitride epitaxial layer 3 and the trapezoidal defects on the surface of the subsequent aluminum gallium nitride material, and obtaining an aluminum gallium nitride material with a smooth surface.

[0035] In step S120 , an aluminum nitride epitaxial layer 3 is grown on the aluminum nitride buffer layer 2 .

[0036] In some exemplary embodiments, growing an aluminum nitride epitaxial layer 3 on the aluminum nitride buffer layer 2 specifically includes: growing the aluminum nitride epitaxial layer 3 according to second process parameters using a metal organic chemical deposition method, the second process parameters including at least one of the following items: a growth temperature of 1140°C ± 10°C; a growth time of 5500s ± 50s; a pressure of 50mbar ± 5mbar; and a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 72 ± 2.

[0037] In the process of growing n-type AlGaN material using the Metal Organic Chemical Vapor Deposition (MOCVD) method, growing AlGaN directly on the sapphire substrate 1 has a large lattice mismatch, so an aluminum nitride buffer layer 2 and an aluminum nitride epitaxial layer 3 are first grown as transition layers to reduce the lattice mismatch.

[0038] In step S130, a superlattice layer 4 is grown on the aluminum nitride epitaxial layer 3, and the superlattice layer 4 includes periodically arranged aluminum nitride sublayers and aluminum gallium nitride sublayers. Optionally, the number of periods of the superlattice layer 4 is 100±5; and / or the molar percentage of aluminum in the superlattice layer 4 is 76%±2%.

[0039] In some exemplary embodiments, growing a superlattice layer 4 on the aluminum nitride epitaxial layer 3 specifically includes: growing the superlattice layer 4 according to a third process parameter using a metal organic chemical deposition method, and the third process parameter includes at least one of the following items: a growth temperature of 1120°C ± 10°C; a growth time of 4500s ± 50s; and a pressure of 100mbar ± 5mbar.

[0040] In step S140, an aluminum gallium nitride layer 5 is grown on the superlattice layer 4. The obtained structure is shown in FIG. Figure 2 Optionally, the molar percentage of aluminum element in the aluminum gallium nitride layer 5 is 57%±2%.

[0041] In some exemplary embodiments, growing the aluminum gallium nitride layer 5 on the superlattice layer 4 specifically includes: growing the aluminum gallium nitride layer 5 according to a fourth process parameter using a metal organic chemical deposition method, the fourth process parameter including at least one of the following items: a growth temperature of 1070°C ± 10°C; a growth time of 3000s ± 50s; a pressure of 100mbar ± 5mbar; and a ratio of a Group V gas source flow rate to a Group III gas source flow rate of 850 ± 10.

[0042] In step S150 , aluminum gallium nitride material is obtained by stripping.

[0043] In an embodiment of the present invention, a precursor material of the nitrogen element in the aluminum nitride buffer layer 2, the aluminum nitride epitaxial layer 3, the aluminum nitride sublayer, the aluminum gallium nitride sublayer and the aluminum gallium nitride layer 5 includes ammonia; and / or a precursor material of the aluminum element in the aluminum nitride buffer layer 2, the aluminum nitride epitaxial layer 3, the aluminum nitride sublayer, the aluminum gallium nitride sublayer and the aluminum gallium nitride layer 5 includes trimethylaluminum; and / or a precursor material of the gallium element in the aluminum gallium nitride sublayer and the aluminum gallium nitride layer 5 includes trimethylgallium.

[0044] For example, step 1: using MOCVD equipment to grow an aluminum nitride buffer layer 2 on a 2-inch sapphire substrate 1, wherein the nucleation pressure of the aluminum nitride buffer layer 2 in sample A is 80 mbar, and the nucleation pressure of the aluminum nitride buffer layer 2 in sample B is 50 mbar. The growth time of both samples is 1300 s, the growth temperature is 1120°C, and the ratio of the group V gas source flow rate to the group III gas source flow rate (V / III) is 1670. Trimethylaluminum (TMAl) and ammonia (NH3) are used as precursor materials for aluminum (Al) and nitrogen (N), respectively.

[0045] Step 2: Continue to grow the aluminum nitride epitaxial layer 3 on sample A and sample B under the same conditions, with a growth time of 5500 s, a growth temperature of 1140° C., a V / III ratio of 72, and a pressure of 50 mbar.

[0046] Step 3: Continue to grow AlN / AlGaN superlattice layer 4 on sample A and sample B under the same conditions. The growth time of both samples is 4500s, the growth temperature is 1120°C, the pressure is 100mbar, the number of periods of AlN / AlGaN superlattice layer 4 is 100, and the molar percentage of aluminum in AlN / AlGaN superlattice layer 4 is 76%. Trimethylgallium (TMGa) is used as a precursor material of gallium (Ga).

[0047] Step 4: Continue to grow the AlGaN layer 5 on sample A and sample B under the same conditions. The growth time of both samples is 3000s, the growth temperature is 1070℃, the pressure is 100mbar, V / III is 850, and the molar percentage of the Al element is 57%. The structure diagrams of sample A and sample B are shown in Figure 2. Figure 2 shown.

[0048] Step 5: Observe sample A and sample B using a scanning electron microscope to obtain a scanned image of sample A as shown in Figure 3 As shown, and the scanned image of sample B is as follows Figure 4 As shown. Figure 3 and Figure 4From the scanning photos in , it can be seen that there are obvious trapezoidal defects on the surface of sample A, while no trapezoidal defects are observed on the surface of sample B. This shows that, under the condition of keeping other conditions unchanged, by reducing the nucleation pressure of the aluminum nitride buffer layer 2, the migration ability of Al atoms can be increased, and the trapezoidal defects on the surface of the aluminum gallium nitride material can be suppressed.

[0049] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an aluminum gallium nitride material, It is characterized in that include: growing an aluminum nitride buffer layer on a sapphire substrate; growing an aluminum nitride epitaxial layer on the aluminum nitride buffer layer; Growing a superlattice layer on the aluminum nitride epitaxial layer, wherein the superlattice layer includes periodically arranged aluminum nitride sublayers and aluminum gallium nitride sublayers; growing an aluminum gallium nitride layer on the superlattice layer; and The aluminum gallium nitride material is obtained by stripping. Wherein, the pressure of growing the aluminum nitride buffer layer on the sapphire substrate does not exceed 50 mbar.

2. The method according to claim 1, It is characterized in that The step of growing an aluminum nitride buffer layer on a sapphire substrate specifically includes: growing the aluminum nitride buffer layer using a metal organic chemical deposition method according to a first process parameter, wherein the first process parameter includes at least one of the following items: Growth temperature is 1120℃±10℃; Growth time: 1300s±50s; The ratio of the Group V gas source flow rate to the Group III gas source flow rate is 1670±20.

3. The method according to claim 1, It is characterized in that The step of growing an aluminum nitride epitaxial layer on the aluminum nitride buffer layer specifically includes: growing the aluminum nitride epitaxial layer using a metal organic chemical deposition method according to a second process parameter, wherein the second process parameter includes at least one of the following items: Growth temperature is 1140℃±10℃; Growth time: 5500s±50s; The pressure is 50mbar±5mbar; The ratio of the Group V gas source flow rate to the Group III gas source flow rate is 72±2.

4. The method according to claim 1, It is characterized in that The step of growing a superlattice layer on the aluminum nitride epitaxial layer specifically includes: growing the superlattice layer using a metal organic chemical deposition method according to a third process parameter, wherein the third process parameter includes at least one of the following items: Growth temperature is 1120℃±10℃; Growth time: 4500s±50s; The pressure is 100mbar±5mbar.

5. The method according to claim 1, It is characterized in that The growing of the aluminum gallium nitride layer on the superlattice layer specifically includes: growing the aluminum gallium nitride layer by metal organic chemical deposition according to a fourth process parameter, wherein the fourth process parameter includes at least one of the following items: Growth temperature is 1070℃±10℃; Growth time: 3000s±50s; The pressure is 100mbar±5mbar; The ratio of the Group V gas source flow rate to the Group III gas source flow rate is 850±10.

6. The method according to any one of claims 1 to 5, It is characterized in that The precursor material of the nitrogen element in the aluminum nitride buffer layer, the aluminum nitride epitaxial layer, the aluminum nitride sublayer, the aluminum gallium nitride sublayer and the aluminum gallium nitride layer includes ammonia; and / or The precursor material of the aluminum element in the aluminum nitride buffer layer, the aluminum nitride epitaxial layer, the aluminum nitride sublayer, the aluminum gallium nitride sublayer and the aluminum gallium nitride layer includes trimethyl aluminum.

7. The method according to any one of claims 1 to 5, It is characterized in that The precursor material of the gallium element in the aluminum gallium nitride sub-layer and the aluminum gallium nitride layer includes trimethyl gallium.

8. The method according to any one of claims 1 to 5, It is characterized in that The number of periods of the superlattice layer is 100±5; and / or The molar percentage of aluminum element in the superlattice layer is 76%±2%.

9. The method according to claim 1, It is characterized in that The molar percentage of aluminum element in the aluminum gallium nitride layer is 57%±2%.

10. An aluminum gallium nitride material, It is characterized in that The method is prepared according to any one of claims 1 to 9.

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