Methods for growing gallium nitride epitaxial layers on silicon and gallium nitride epitaxial wafers

Abstract

This invention discloses a method for growing a silicon-based gallium nitride (GaN) epitaxial layer and a GaN epitaxial wafer. The method for growing the GaN epitaxial layer includes: placing a silicon substrate in a reaction chamber; growing an aluminum nitride (A) buffer layer on the silicon substrate; growing a gallium aluminum nitride (GaA) buffer layer on the A A B buffer layer; growing a gallium indium (GaIn) insertion layer on the A A B buffer layer; and growing a GaN epitaxial layer on the GaIn insertion layer. The temperature at which the GaIn insertion layer is grown is lower than the temperature at which the A B B buffer layer and the GaN epitaxial layer are grown. During the cooling process, cracks appear in the A B B buffer layer and the A B B buffer layer, releasing some of the stress in the buffer layer. Simultaneously, the growth of the GaIn insertion layer covers the cracks. Subsequently, the temperature is raised to grow the GaN epitaxial layer, allowing it to withstand greater and longer compressive stress during growth.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more particularly to a method for growing a silicon-based gallium nitride epitaxial layer and a gallium nitride epitaxial wafer. Background Technology

[0002] Gallium nitride (GaN) is a type of wide bandgap semiconductor material with characteristics such as a large adjustable bandgap, high breakdown field strength, and high electron saturation drift velocity. Light-emitting diodes, laser diodes, photodetectors, and high electron mobility field-effect transistors fabricated with GaN as the core have wide applications in lighting displays, microwave power, and power electronics.

[0003] Silicon (Si) substrates are generally used in optoelectronic devices. Si substrates can be mass-produced in large sizes. Epitaxial GaN-based devices on Si substrates can significantly increase the number of devices obtained by single-wafer epitaxy and reduce the epitaxial cost of GaN-based devices. Therefore, Si-based GaN is highly favored by the industry.

[0004] However, the significant differences in lattice constants and coefficients of thermal expansion between Si and GaN materials result in high dislocation surface density and high stress in Si-based GaN materials, making it difficult to achieve high-quality, high-thickness, crack-free epitaxial growth of Si-based GaN materials. Currently, the epitaxial growth of Si-based GaN materials mainly involves growing an AlGaN stress buffer layer with a certain gradient to introduce compressive stress, thereby counteracting the thermal stress in the Si-based GaN material system during cooling and preventing cracking in GaN. However, due to the large number of penetrating dislocations in the Si-based GaN material system, under the drive of compressive stress, these penetrating dislocations climb and tilt, forming mismatched dislocations perpendicular to the growth direction. The formation of these mismatched dislocations consumes the compressive stress, weakening it and making it insufficient to compensate for the thermal stress during cooling, leading to cracking in the GaN material. Summary of the Invention

[0005] To address the above problems, this invention provides a method for growing a silicon-based gallium nitride epitaxial layer and a gallium nitride epitaxial wafer. By growing a gallium nitride indium insertion layer at a lower temperature, crack-free epitaxial growth of Si-based GaN can be achieved.

[0006] To achieve the above objectives, the present invention provides a method for growing a silicon-based gallium nitride epitaxial layer, comprising:

[0007] The silicon substrate is placed in the reaction chamber;

[0008] An aluminum nitride buffer layer is grown on a silicon substrate;

[0009] A gallium aluminum nitride buffer layer is grown on an aluminum nitride buffer layer;

[0010] A gallium nitride indium insertion layer is grown on a gallium nitride aluminum buffer layer;

[0011] A gallium nitride epitaxial layer is grown on a gallium nitride indium insertion layer;

[0012] The temperature at which the gallium nitride indium insertion layer is grown is lower than the temperature at which the gallium nitride aluminum buffer layer and the gallium nitride epitaxial layer are grown.

[0013] According to an embodiment of the present invention, the gallium indium nitride (GaN) insertion layer is grown on the gallium aluminum nitride (GaN) buffer layer in a coherent manner, so that the lattice constant of GaN in the GaN insertion layer is the same as that of GaN in the GaN buffer layer.

[0014] According to an embodiment of the present invention, growing an aluminum nitride buffer layer on a silicon substrate includes:

[0015] The reaction chamber temperature is set at 900-1200℃ and the pressure at 50-200mbar.

[0016] An aluminum source is introduced into the reaction chamber, and a nitrogen source is added after 10-50 seconds. An aluminum nitride buffer layer with a thickness of 100-300 nm is grown on a silicon substrate.

[0017] According to an embodiment of the present invention, growing a gallium aluminum nitride buffer layer on an aluminum nitride buffer layer includes:

[0018] The reaction chamber temperature is set at 910-1100℃ and the pressure at 100-300mbar.

[0019] An aluminum source, a gallium source, and a nitrogen source are introduced into the reaction chamber, and then the aluminum source is slowly reduced to grow a gallium aluminum nitride buffer layer with a composition gradient on the aluminum nitride buffer layer. The growth rate of the gallium aluminum nitride buffer layer is 0.5-1 μm / h, the thickness is 200-1200 nm, and the aluminum content in the layer gradually decreases from bottom to top, with the aluminum content at the bottom being 50%.

[0020] According to an embodiment of the present invention, the growth temperature of the gallium indium nitride intercalation layer is 700-900℃, the growth pressure is 350-500mbar, the growth rate is 0.05-0.15um / h, the thickness of the gallium indium nitride intercalation layer is 1-150nm, and the composition of indium element is 0%-5%.

[0021] According to an embodiment of the present invention, the growth temperature of the gallium nitride epitaxial layer is 1000-1100℃, and the growth pressure is 200-400mbar.

[0022] According to an embodiment of the present invention, it further includes:

[0023] After placing the silicon substrate in the reaction chamber, hydrogen gas is introduced at 1000-1100°C to remove oxides from the surface of the silicon substrate.

[0024] The present invention also provides a gallium nitride epitaxial wafer grown by the above-described growth method, comprising:

[0025] Silicon substrate;

[0026] An aluminum nitride buffer layer is located above a silicon-based substrate;

[0027] A gallium nitride aluminum buffer layer is located above the aluminum nitride buffer layer;

[0028] A gallium nitride indium insertion layer is located above a gallium nitride aluminum buffer layer;

[0029] A gallium nitride epitaxial layer is located above a gallium nitride indium insertion layer;

[0030] The growth temperature of the gallium nitride indium insertion layer is lower than that of the gallium nitride aluminum buffer layer and the gallium nitride epitaxial layer.

[0031] According to an embodiment of the present invention, the lattice constant of gallium indium nitride in the gallium indium nitride insertion layer is the same as the lattice constant of gallium aluminum nitride in the gallium aluminum nitride buffer layer.

[0032] According to an embodiment of the present invention, the thickness of the aluminum nitride buffer layer is 100-300 nm;

[0033] The thickness of the gallium nitride aluminum buffer layer is 200-1200nm. The aluminum content in the gallium nitride aluminum buffer layer gradually decreases from bottom to top, with the aluminum content at the bottom being 50%.

[0034] The thickness of the gallium nitride indium intercalation layer is 0-150 nm, and the indium content is 0%-5%.

[0035] The dislocation density in gallium nitride epitaxial layers is less than 10. 8 cm -2 .

[0036] According to the method for growing a silicon-based gallium nitride epitaxial layer and the gallium nitride epitaxial wafer provided by the present invention, a gallium nitride indium insertion layer is grown on a gallium nitride aluminum buffer layer by cooling. During the cooling process, cracks appear in the aluminum nitride buffer layer and the gallium nitride aluminum buffer layer, releasing part of the stress in the buffer layer. At the same time, the growth of the gallium nitride indium insertion layer can cover the cracks, providing a good foundation for the growth of the gallium nitride epitaxial layer. Subsequently, the gallium nitride epitaxial layer is grown by heating, which enables the gallium nitride epitaxial layer to be subjected to greater and longer compressive stress during growth without affecting the surface condition of the gallium nitride epitaxial layer, thus achieving the growth of a crack-free gallium nitride epitaxial layer. Attached Figure Description

[0037] Figure 1 The schematic diagram illustrates the steps of a method for growing a silicon-based gallium nitride epitaxial layer according to an embodiment of the present invention;

[0038] Figure 2aThis schematically illustrates in-situ curvature monitoring at various stages in the existing gallium nitride epitaxial layer growth method;

[0039] Figure 2b The diagram schematically illustrates the in-situ curvature monitoring at each stage of the gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0040] Figure 3 The diagram schematically illustrates the lattice relaxation process of each layer of material in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0041] Figure 4a This schematic diagram illustrates the surface morphology after the growth of the AlGaN buffer layer in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0042] Figure 4b This schematic diagram illustrates the surface morphology after the AlGaN buffer layer growth is completed and the temperature is lowered in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0043] Figure 4c This schematic diagram illustrates the surface morphology after the InGaN insertion layer growth is completed in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0044] Figure 4d This schematic diagram illustrates the surface morphology after GaN epitaxial layer growth in a gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0045] Figure 5 This diagram illustrates the effect of temperature on the lattice constant in a gallium nitride epitaxial layer growth method according to an embodiment of the present invention.

[0046] Figure 6 A cross-sectional view of a gallium nitride epitaxial wafer according to an embodiment of the present invention is shown schematically.

[0047] [Attached image labels]

[0048] 1-Silicon substrate; 2-Aluminum nitride buffer layer; 3-Gallium nitride aluminum buffer layer; 4-Gallium nitride indium insertion layer; 5-Gallium nitride epitaxial layer. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0050] This invention provides a method for growing a silicon-based gallium nitride epitaxial layer, comprising:

[0051] The silicon substrate is placed in the reaction chamber;

[0052] An aluminum nitride buffer layer is grown on a silicon substrate;

[0053] A gallium aluminum nitride buffer layer is grown on an aluminum nitride buffer layer;

[0054] A gallium nitride indium insertion layer is grown on a gallium nitride aluminum buffer layer;

[0055] A gallium nitride epitaxial layer is grown on a gallium nitride indium insertion layer;

[0056] The temperature at which the gallium nitride indium insertion layer is grown is lower than the temperature at which the gallium nitride aluminum buffer layer and the gallium nitride epitaxial layer are grown.

[0057] According to the method for growing a silicon-based gallium nitride epitaxial layer and the gallium nitride epitaxial wafer provided by the present invention, a gallium nitride indium insertion layer is grown on a gallium nitride aluminum buffer layer by cooling. During the cooling process, cracks appear in the aluminum nitride buffer layer and the gallium nitride aluminum buffer layer, releasing part of the stress in the buffer layer. At the same time, the growth of the gallium nitride indium insertion layer can cover the cracks, providing a good foundation for the growth of the gallium nitride epitaxial layer. Subsequently, the gallium nitride epitaxial layer is grown by heating, which enables the gallium nitride epitaxial layer to be subjected to greater and longer compressive stress during growth without affecting the surface condition of the gallium nitride epitaxial layer, thus achieving the growth of a crack-free gallium nitride epitaxial layer.

[0058] Figure 1 The diagram schematically illustrates the steps of a method for growing a gallium nitride epitaxial layer on silicon according to an embodiment of the present invention. Figure 1 As shown, the method for growing a silicon-based gallium nitride epitaxial layer includes steps S1 to S6.

[0059] Operation S1 involves placing a silicon (Si) substrate into the reaction chamber.

[0060] In operation S2, an aluminum nitride (AlN) buffer layer is grown on a silicon substrate.

[0061] In operation S3, a gallium aluminum nitride (AlGaN) buffer layer is grown on the aluminum nitride buffer layer.

[0062] In operation S4, an indium gallium nitride (InGaN) insertion layer is grown on the aluminum gallium nitride buffer layer.

[0063] In operation S5, a gallium nitride (GaN) epitaxial layer is grown on the gallium nitride indium insertion layer.

[0064] According to an embodiment of the present invention, the temperature at which the InGaN insertion layer is grown is lower than the temperature at which the AlGaN buffer layer and the GaN epitaxial layer are grown.

[0065] According to an embodiment of the present invention, the gallium indium nitride (GaN) insertion layer is grown on the gallium aluminum nitride (GaN) buffer layer in a coherent manner, so that the lattice constant of GaN in the GaN insertion layer is the same as that of GaN in the GaN buffer layer.

[0066] According to an embodiment of the present invention, after the silicon substrate is placed in the reaction chamber, hydrogen gas is introduced at a temperature of 1000-1100°C, for example, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C, or 1100°C, to remove oxides on the surface of the silicon substrate.

[0067] According to an embodiment of the present invention, step S2 includes:

[0068] Set the reaction chamber temperature to 900-1200℃, for example, reaction chamber temperatures of 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃, 1100℃, 1120℃, 1140℃, 1160℃, 1180℃, or 1200℃, and the pressure to 50-200mbar, for example, pressures of 50mbar, 60mbar, 80mbar, 100mbar, 120mbar, 140mbar, 160mbar, 180mbar, or 200mbar;

[0069] An aluminum source is introduced into the reaction chamber, and a nitrogen source is added after 10-50 seconds. An AlN buffer layer is grown on a silicon substrate. The thickness of the AlN buffer layer is 100-300 nm, for example, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, or 300 nm.

[0070] According to an embodiment of the present invention, step S3 includes:

[0071] Set the reaction chamber temperature to 910-1100℃, for example, reaction chamber temperatures of 910℃, 920℃, 940℃, 960℃, 980℃, 1000℃, 1020℃, 1040℃, 1060℃, 1080℃, or 1100℃, and the pressure to 100-300mbar, for example, pressures of 100mbar, 120mbar, 140mbar, 160mbar, 180mbar, 200mbar, 220mbar, 240mbar, 260mbar, 280mbar, or 300mbar;

[0072] An aluminum source, a gallium source, and a nitrogen source are introduced into the reaction chamber, and then the introduction of the aluminum source is slowly reduced to grow an AlGaN buffer layer with a compositional gradient on the aluminum nitride buffer layer.

[0073] According to an embodiment of the present invention, the growth rate of the AlGaN buffer layer in step S3 is 0.5-1 μm / h, for example, a growth rate of 0.5 μm / h, 0.6 μm / h, 0.7 μm / h, 0.8 μm / h, 0.9 μm / h, or 1.0 μm / h, and the thickness is 200-1200 nm, for example, a thickness of 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, or 1200 nm. The aluminum element composition in the layer gradually decreases from bottom to top, and the aluminum element composition at the bottom is 50%.

[0074] According to an embodiment of the present invention, the growth temperature in step S4 is 700-900℃, for example, 700℃, 720℃, 740℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃, or 900℃; the growth pressure is 350-500 mbar, for example, 350 mbar, 360 mbar, 380 mbar, 400 mbar, 420 mbar, 440 mbar, 460 mbar, 480 mbar, or 500 mbar; and the growth rate is 0.05-0.15 μm / h, for example, 0.05 μm / h, 0.06 μm / h, 0.07 μm / h, 0.08 μm / h, or 0.09 μm / h. The InGaN insertion layer has a thickness of 1-150 nm, such as 1 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, or 150 nm. The indium content is 0.1%-5%, such as 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5.0%, to ensure that the InGaN insertion layer is coherently grown on the AlGaN buffer layer.

[0075] According to an embodiment of the present invention, the growth temperature in step S5 is 1000-1100℃, for example, 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, or 1100℃, and the growth pressure is 200-400mbar, for example, 200mbar, 220mbar, 240mbar, 260mbar, 280mbar, 300mbar, 320mbar, 340mbar, 360mbar, 380mbar, or 400mbar.

[0076] According to an embodiment of the present invention, the dislocation density of the GaN epitaxial layer is less than 10. 8 cm -2 There are no cracks outside the edge area.

[0077] According to an embodiment of the present invention, during the actual growth process, the stress condition of the epitaxial film is determined using an in-situ curvature monitoring system, and the stress formula is:

[0078]

[0079] Where, σ m E represents the stress magnitude of the epitaxial thin film. s h s and ν s These represent the substrate's modulus, thickness, and Poisson's ratio, respectively; h f κ represents the thickness of the epitaxial film; κ represents the curvature.

[0080] According to formula (1), the stress can be obtained by calculating the slope of the curve obtained by the monitoring system to obtain the relationship between curvature and time. Qualitatively, when the curvature is positive, the epitaxial film is subjected to tensile stress; when the curvature is negative, the epitaxial film is subjected to compressive stress.

[0081] Figure 2a This schematically illustrates in-situ curvature monitoring at various stages in the existing gallium nitride epitaxial layer growth method; Figure 2b The diagram schematically illustrates in-situ curvature monitoring at various stages of a gallium nitride epitaxial layer growth method according to an embodiment of the present invention. Figure 2a , 2b As shown, Figure 2a In the diagram, S2a is the AlN buffer layer growth stage, S3a is the AlGaN buffer layer growth stage, S4a is the GaN epitaxial layer growth stage, and S5a is the cooling stage. Figure 2b In the diagram, S2b represents the AlN buffer layer growth stage, S3b represents the AlGaN buffer layer growth stage, S4b represents the InGaN insertion layer growth stage, including the heating and cooling processes during growth, S5b represents the GaN epitaxial layer growth stage, and S6b represents the cooling stage.

[0082] Combining formula (1) Figure 2a , 2b To conduct analysis, Figure 2aIn the AlN buffer layer growth stage S2a, the epitaxial film, i.e., the AlN buffer layer, is subjected to tensile stress for most of the time. In the AlGaN buffer layer growth stage S3a, the epitaxial film, i.e., the AlGaN buffer layer, is first subjected to tensile stress and then to compressive stress. In the GaN epitaxial layer growth stage S4a, the epitaxial film, i.e., the GaN epitaxial layer, is subjected to compressive stress. However, as the GaN epitaxial layer grows, the compressive stress is consumed and gradually decreases. In the cooling stage S5a, the film is subjected to tensile stress for most of the time. It can be seen that in stage S4a, the compressive stress on the GaN epitaxial layer before the growth is completed has been almost completely consumed. Figure 2b In the AlN buffer layer growth stage S2b, the epitaxial film, i.e., the AlN buffer layer, is subjected to tensile stress for most of the time; in the AlGaN buffer layer growth stage S3b, the epitaxial film, i.e., the AlGaN buffer layer, is first subjected to tensile stress and then to compressive stress; in the InGaN insertion layer growth stage S4b, the epitaxial film, i.e., the InGaN insertion layer, is first subjected to tensile stress, which is caused by the cooling process required for the growth of the InGaN insertion layer, and then it is converted into compressive stress, including the compressive stress experienced during the growth of the InGaN insertion layer and the compressive stress caused by the heating process required for the subsequent growth of the GaN epitaxial layer; in the GaN epitaxial layer growth stage S5b, the GaN epitaxial layer is continuously subjected to compressive stress; in the cooling stage S6b, the film is first subjected to compressive stress and then to tensile stress.

[0083] Based on the above analysis, in the existing gallium nitride epitaxial layer growth method and the gallium nitride epitaxial layer growth method in the embodiments of the present invention, the stress states of the AlN buffer layer and the AlGaN buffer layer are roughly the same. However, the gallium nitride epitaxial layer growth method in the embodiments of the present invention adds an InGaN insertion layer, so that the GaN epitaxial layer growth stage in the gallium nitride epitaxial layer growth method in the embodiments of the present invention can be continuously subjected to compressive stress.

[0084] Figure 3 The diagram schematically illustrates the lattice relaxation process of each layer in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention. The lattice relaxation process is the process of change in the lattice constant. Under normal conditions, the lattice constants are Si > InN > GaN > AlN. The lattice constant of the ternary alloy InGaN is between that of InN and GaN, and the lattice constant of AlGaN is between that of GaN and AlN. That is, the lattice constants are Si > InN > InGaN > GaN > AlGaN > AlN. Figure 3As shown, the Si substrate does not undergo lattice relaxation, and its lattice constant remains unchanged, resulting in a rectangular shape. The AlN buffer layer grown on the Si substrate exhibits a trapezoidal shape because the lattice constant Si > AlN, thus decreasing from bottom to top. The AlGaN buffer layer grown on the AlN buffer layer exhibits an inverted trapezoidal shape because the lattice constant AlGaN > AlN, thus increasing from bottom to top. The InGaN insertion layer grown on the AlGaN buffer layer exhibits a rectangular shape because InGaN is coherently grown and does not undergo relaxation; its overall lattice remains unchanged, maintaining the same lattice constant as the topmost AlGaN lattice. The GaN epitaxial layer grown on the InGaN insertion layer exhibits an inverted trapezoidal shape because the lattice constant GaN > AlGaN = coherently grown InGaN, thus increasing from bottom to top.

[0085] According to an embodiment of the present invention, since the lattice constant of InGaN material is greater than that of AlGaN material under normal conditions, the InGaN insertion layer will be subjected to compressive stress when grown in a coherent manner, which will prevent the lattice constant of the InGaN insertion layer from being greater than that of GaN and thus prevent the GaN material from being subjected to tensile stress during growth.

[0086] According to embodiments of the present invention, maintaining coherent growth of the InGaN insertion layer requires selecting growth parameters, the thickness of the InGaN insertion layer, and its composition.

[0087] According to an embodiment of the present invention, due to the difference in the coefficients of thermal expansion in the Si-based GaN material system, the thin film is subjected to a large amount of tensile stress during the cooling process. Therefore, cracks may form during the cooling process after the AlGaN buffer layer growth is completed due to insufficient compressive stress to compensate for the tensile stress. However, after the cracks form, it is the InGaN insertion layer that continues to grow, not the GaN epitaxial layer. The growth of the insertion layer is still sufficient to fill the cracks in the AlGaN buffer layer, so that the surface of the GaN epitaxial layer is not affected. In addition, the cracks in the AlN buffer layer can provide a channel for the release of thermal stress during the cooling process after the GaN epitaxial layer growth is completed.

[0088] Figure 4a This schematically illustrates the surface morphology after the growth of the AlGaN buffer layer in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention. Figure 4a As shown, there are no cracks on the surfaces of the AlN buffer layer and the AlGaN buffer layer.

[0089] Figure 4b This schematic diagram illustrates the surface morphology after the AlGaN buffer layer growth is completed and the temperature is lowered in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention. Figure 4b As shown, cracks appear on the surfaces of the AlN buffer layer and the AlGaN buffer layer due to cooling.

[0090] Figure 4c This schematically illustrates the surface morphology after the InGaN insertion layer growth is completed in the gallium nitride epitaxial layer growth method according to an embodiment of the present invention. Figure 4c As shown, the growth of the InGaN insertion layer fills the cracks in the AlGaN buffer layer, providing a good growth foundation for the GaN epitaxial layer.

[0091] Figure 4d This schematically illustrates the surface morphology after GaN epitaxial layer growth in a gallium nitride epitaxial layer growth method according to an embodiment of the present invention. Figure 4d As shown, there are no cracks on the surface after the GaN epitaxial layer growth is completed.

[0092] According to an embodiment of the present invention, an InGaN insertion layer is grown on an AlGaN buffer layer by cooling. During the cooling process, cracks appear in the AlN buffer layer and the AlGaN buffer layer, releasing some of the stress in the buffer layer. At the same time, the growth of the InGaN insertion layer can cover the cracks, providing a good foundation for the growth of the GaN epitaxial layer.

[0093] Figure 5 This diagram schematically illustrates the effect of temperature on the lattice constant in a gallium nitride epitaxial layer growth method according to an embodiment of the present invention. The thermal expansion coefficients are in the order: GaN > AlN > InN. Figure 5 As shown, A represents the lattice constant of AlN material at the AlN buffer layer growth temperature, and B represents the lattice constant of AlN material at the InGaN insertion layer growth temperature. During the cooling process after the AlGaN buffer layer growth is complete, because the coefficient of thermal expansion of AlGaN is greater than that of AlN, the lattice constant of the AlGaN / AlN system after cooling is lower than that of AlN at the InGaN material growth temperature. During the heating process after the InGaN insertion layer growth is complete, because the coefficient of thermal expansion of InGaN is smaller than that of AlN and AlGaN, the lattice constant of the system cannot be restored to the original lattice constant of the AlGaN / AlN system at the same temperature. Therefore, growing a GaN epitaxial layer on the InGaN / AlGaN / AlN system results in greater compressive stress compared to growing a GaN epitaxial layer on the AlGaN / AlN system, which is beneficial for improving the occurrence of cracks in the GaN epitaxial layer.

[0094] According to embodiments of the present invention, during the cooling growth of the InGaN insertion layer, cracks may appear in the AlN and AlGaN buffer layers, releasing some of the stress in the buffer layers. Subsequently, the InGaN insertion layer grows and covers the cracks, without affecting the GaN surface condition. Simultaneously, the cooling and heating process allows the GaN epitaxial layer to withstand greater and longer compressive stress compared to direct growth on the AlGaN buffer layer, effectively reducing defects on the GaN epitaxial layer surface and achieving the growth of a crack-free gallium nitride epitaxial layer.

[0095] According to an embodiment of the present invention, since the InN bond energy (1.93eV) is less than the AlN bond energy (2.88eV), high temperature will cause the In-N bond to break and affect the incorporation of In. InGaN materials are usually grown at a lower temperature. Growing InGaN under low temperature conditions can reduce the dislocations introduced during epitaxial growth.

[0096] The present invention also provides a gallium nitride epitaxial wafer grown by the method described above. Figure 6 A cross-sectional view of a gallium nitride epitaxial wafer according to an embodiment of the present invention is schematically shown, such as... Figure 6 As shown, the gallium nitride epitaxial wafer includes: a silicon substrate 1; an aluminum nitride buffer layer 2 located above the silicon substrate 1; an aluminum gallium nitride buffer layer 3 located above the aluminum nitride buffer layer 2; an indium gallium nitride insertion layer 4 located above the aluminum gallium nitride buffer layer 3; and a gallium nitride epitaxial layer 5 located above the indium gallium nitride insertion layer 4; wherein the growth temperature of the indium gallium nitride insertion layer 4 is lower than the growth temperature of the aluminum gallium nitride buffer layer 3 and the gallium nitride epitaxial layer 5.

[0097] According to an embodiment of the present invention, the lattice constant of gallium indium nitride in the gallium indium nitride insertion layer is the same as the lattice constant of gallium aluminum nitride in the gallium aluminum nitride buffer layer.

[0098] According to an embodiment of the present invention, the thickness of the aluminum nitride buffer layer is 100-300 nm, for example, the thickness of the AlN buffer layer is 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, or 300 nm.

[0099] The thickness of the gallium nitride aluminum buffer layer is 200-1200nm. For example, the thickness of the AlGaN buffer layer is 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm, or 1200nm. The aluminum content in the gallium nitride aluminum buffer layer gradually decreases from bottom to top, and the aluminum content at the bottom is 50%.

[0100] The thickness of the gallium nitride indium intercalation layer is 1-150 nm, for example, the thickness of the InGaN intercalation layer is 1 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, or 150 nm, and the indium element composition is 0.1%-5%, for example, the indium element composition is 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5.0%;

[0101] The dislocation density in gallium nitride epitaxial layers is less than 10. 8 cm -2 .

[0102] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely 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 within the protection scope of the present invention.

Claims

1. A method for growing a silicon-based gallium nitride epitaxial layer, comprising: The silicon substrate is placed in the reaction chamber; An aluminum nitride buffer layer is grown on the silicon substrate; A gallium aluminum nitride buffer layer is grown on the aluminum nitride buffer layer; A gallium indium nitride (GaN) insertion layer is grown on the gallium aluminum nitride (GaN) buffer layer. The GaN insertion layer is grown coherently on the GaN buffer layer so that the lattice constant of GaN in the GaN insertion layer is the same as that of GaN in the GaN buffer layer. A gallium nitride epitaxial layer is grown on the gallium nitride indium insertion layer; The temperature at which the gallium nitride indium intercalation layer is grown is lower than the temperature at which the gallium nitride aluminum buffer layer and the gallium nitride epitaxial layer are grown; and The growth temperature of the gallium nitride indium intercalation layer is 700-900 ℃, the growth pressure is 350-500 mbar, the growth rate is 0.05-0.15 μm / h, the thickness of the gallium nitride indium intercalation layer is 1-150 nm, and the indium element composition is 0.1%-5%.

2. The growth method according to claim 1, wherein, Growing an aluminum nitride buffer layer on the silicon substrate includes: The reaction chamber temperature is set at 900–1200 ℃ and the pressure at 50–200 mbar. An aluminum source is introduced into the reaction chamber, and a nitrogen source is added after 10–50 s. An aluminum nitride buffer layer with a thickness of 100–300 nm is grown on the silicon substrate.

3. The growth method according to claim 1, wherein, Growing a gallium aluminum nitride buffer layer on the aluminum nitride buffer layer includes: The reaction chamber temperature was set at 910–1100 ℃ and the pressure at 100–300 mbar. An aluminum source, a gallium source, and a nitrogen source are introduced into the reaction chamber, and then the introduction of the aluminum source is slowly reduced to grow a gallium aluminum nitride buffer layer with a composition gradient on the aluminum nitride buffer layer. The growth rate of the gallium aluminum nitride buffer layer is 0.5-1 μm / h, the thickness is 200-1200 nm, and the aluminum content in the layer gradually decreases from bottom to top, with the aluminum content at the bottom being 50%.

4. The growth method according to claim 1, wherein, The growth temperature of the gallium nitride epitaxial layer is 1000-1100℃, and the growth pressure is 200-400 mbar.

5. The growth method according to claim 1, further comprising: After placing the silicon substrate in the reaction chamber, hydrogen gas is introduced at 1000-1100 °C to remove oxides from the surface of the silicon substrate.

6. A gallium nitride epitaxial wafer grown by the growth method according to any one of claims 1 to 5, comprising: Silicon substrate; An aluminum nitride buffer layer is located above the silicon substrate; A gallium nitride aluminum buffer layer is located above the aluminum nitride buffer layer; A gallium indium nitride (GaN) insertion layer is located above the gallium aluminum nitride (GaN) buffer layer, wherein the lattice constant of GaN in the GaN insertion layer is the same as that of GaN in the gallium aluminum nitride (GaN) buffer layer. A gallium nitride epitaxial layer is located above the gallium nitride indium insertion layer; Wherein, the growth temperature of the gallium nitride indium insertion layer is lower than the growth temperature of the gallium nitride aluminum buffer layer and the gallium nitride epitaxial layer; and The thickness of the gallium nitride indium insertion layer is 1-150 nm, and the indium element composition is 0.1%-5%.

7. The gallium nitride epitaxial wafer according to claim 6, wherein, The thickness of the aluminum nitride buffer layer is 100-300 nm; The thickness of the gallium nitride aluminum buffer layer is 200-1200 nm, and the aluminum content in the gallium nitride aluminum buffer layer gradually decreases from bottom to top, with the aluminum content at the bottom being 50%. The dislocation density in the gallium nitride epitaxial layer is less than 10. 8 cm －2 .

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