SiC-based GaN epitaxial structure and preparation method and device thereof

Abstract

The invention relates to a SiC-based GaN epitaxial structure and a preparation method and device thereof, in particular to the field of semiconductors, and the SiC-based GaN epitaxial structure comprises a GaN channel layer, an AlN insertion layer and an AlGaN barrier layer which are sequentially arranged on a substrate; and the substrate comprises a semi-insulating substrate doped with Fe-SiC (silicon carbide). According to the SiC-based GaN epitaxial structure provided by the invention, the substrate is made to be a semi-insulating substrate by doping Fe into the substrate, so that optimization of the SiC-based GaN epitaxial structure can be realized without arranging a high-resistance layer, and the obtained epitaxial structure can avoid electric leakage, namely high-voltage breakdown, has relatively high breakdown voltage and also has a good heat dissipation effect.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, specifically to a SiC-based GaN epitaxial structure, its preparation method, and devices. Background Technology

[0002] Currently, with the rapid development of 5G mobile communication, radar, satellite communication, and next-generation power electronics technologies, the performance of traditional first-generation (silicon-Si) and second-generation (gallium arsenide-GaAs) semiconductor materials under extreme operating conditions such as high frequency, high power, and high temperature has approached its physical limits. To overcome this bottleneck, third-generation semiconductor materials, represented by gallium nitride (GaN) and silicon carbide (SiC), have emerged, becoming the core engine supporting the future upgrading of information technology and energy technology industries.

[0003] Epitaxial growth of GaN heterojunction structures (GaN-on-SiC) on SiC substrates has become the preferred method for fabricating high-performance radio frequency (RF) microwave devices and high-end power electronic devices due to its superior overall performance.

[0004] GaN, as the active layer, possesses high two-dimensional electron gas (2DEG) density and mobility: the heterojunction interface formed by GaN and AlGaN can generate a highly concentrated and rapidly mobile two-dimensional electron gas, achieving a highly conductive channel without doping. This results in devices with extremely high cutoff frequencies (fT) and maximum oscillation frequencies (fmax), making them ideal for high-frequency applications. High breakdown electric field: GaN's breakdown electric field is as high as 3.3 MV / cm, 10 times that of Si, enabling it to withstand higher operating voltages and resulting in higher power density. Strong electron saturation velocity: ensures the device's high efficiency at high frequencies.

[0005] SiC, as an ideal substrate material, possesses excellent thermal conductivity, which is its most critical advantage. Its thermal conductivity (~370 W / mK) is three times that of Si and ten times that of GaAs. For high-power devices, efficient heat dissipation is a prerequisite for ensuring performance, reliability, and lifespan. SiC substrates can rapidly conduct heat generated in the GaN active region, preventing chip overheating. Good lattice matching and thermal expansion coefficient matching: The lattice mismatch between SiC and GaN (~3.5%) is relatively small, allowing for the growth of GaN epitaxial layers with low defect density and high crystal quality on SiC, thus ensuring device performance and reliability. The close similarity in their thermal expansion coefficients also reduces thermal stress generated when cooling down from the growth temperature.

[0006] For example, CN118422329A discloses an epitaxial growth method for an iron-doped GaN buffer layer and a GaN microwave power device. An AlN nucleation layer is grown on a SiC single crystal substrate using metal-organic chemical vapor deposition. Then, an iron-doped GaN buffer layer is grown on the AlN nucleation layer. The pressure of the reaction chamber is 600~1000 mbar. The V / III ratio introduced into the reaction chamber is (100~300):1. The molar flux ratio of the Fe source to the Ga source is 1E-5~1E-3.

[0007] It is known that in the current process of SiC-based GaN epitaxial growth, it is necessary to grow a layer of Fe-doped GaN high-resistivity layer. This layer provides an insulating wall for radio frequency devices and reduces leakage current. However, growing Fe-GaN layer will encounter the following problems: Fe memory contamination, Fe residue in the cavity, low GaN thermal conductivity, and high thermal resistance of high-resistivity layer Fe-GaN. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a SiC-based GaN epitaxial structure and its preparation method and device, so as to solve the defects of Fe memory contamination in the growth of Fe-GaN layer, Fe residue in cavity, low thermal conductivity of GaN and high thermal resistance of high-resistivity Fe-GaN layer, resulting in poor heat dissipation performance of epitaxial structure.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a SiC-based GaN epitaxial structure, the SiC-based GaN epitaxial structure comprising:

[0011] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0012] The substrate includes: an Fe-doped SiC semi-insulating substrate.

[0013] The SiC-based GaN epitaxial structure provided by this invention optimizes the SiC-based GaN epitaxial structure by doping Fe into the substrate to make the substrate a semi-insulating substrate, thus eliminating the need for a high-resistivity layer. This results in an epitaxial structure that avoids leakage current and breakdown at high voltages, possesses a high breakdown voltage, and also has good heat dissipation.

[0014] As a preferred embodiment of the present invention, the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 1×10⁻⁶. 16 -1×10 17 pcs / cm 3 .

[0015] Preferably, the resistivity of the Fe-doped SiC semi-insulating substrate is >1×10⁻⁶. 9 Ω·cm.

[0016] As a preferred embodiment of the present invention, the thickness of the GaN channel layer is 50-200 nm.

[0017] Preferably, the thickness of the AlN insertion layer is 1-1.5 nm.

[0018] Preferably, the thickness of the AlGaN barrier layer is 20-30 nm.

[0019] In a second aspect, the present invention provides a method for preparing a SiC-based GaN epitaxial structure as described in the first aspect, the method comprising:

[0020] GaN channel layer growth, AlN insertion layer growth, and AlGaN barrier layer growth were performed sequentially on a Fe-doped SiC semi-insulating substrate to obtain a SiC-based GaN epitaxial structure.

[0021] As a preferred embodiment of the present invention, the flow rate of the carrier gas used in the growth of the GaN channel layer is 150-200 slm.

[0022] Preferably, the flow rate of the Ga source used in the growth of the GaN channel layer is 200-300 sccm.

[0023] Preferably, the flow rate of the nitrogen source used in the GaN channel layer growth is 30-100 slm.

[0024] As a preferred embodiment of the present invention, the growth temperature of the GaN channel layer is 1100-1120℃.

[0025] Preferably, the growth pressure for growing the GaN channel layer is 100-200 mbar.

[0026] As a preferred embodiment of the present invention, the flow rate of the carrier gas used in the growth of the AlN insertion layer is 50-100 slm.

[0027] Preferably, the flow rate of the Al source used in the growth of the AlN insertion layer is 40-60 sccm.

[0028] Preferably, the flow rate of the nitrogen source used in the growth of the AlN insertion layer is 1-5 slm.

[0029] As a preferred embodiment of the present invention, the growth temperature of the AlN insertion layer is 1100-1120℃.

[0030] Preferably, the growth pressure for growing the AlN insertion layer is 100-200 mbar.

[0031] As a preferred embodiment of the present invention, the flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 50-100 slm.

[0032] Preferably, the flow rate of the Ga source used in the growth of the AlGaN barrier layer is 50-100 sccm.

[0033] Preferably, the nitrogen source used in the growth of the AlGaN barrier layer has a flow rate of 1-5 slm.

[0034] Preferably, the flow rate of the Al source used in the growth of the AlGaN barrier layer is 50-200 sccm.

[0035] Preferably, the growth temperature of the AlGaN barrier layer is 1100-1120℃.

[0036] Preferably, the growth pressure for growing the AlGaN barrier layer is 100-200 mbar.

[0037] Thirdly, the present invention provides a device comprising: a SiC-based GaN epitaxial structure as described in the first aspect.

[0038] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0039] This invention provides a GaN epitaxial structure. By optimizing the substrate composition, the GaN epitaxial structure can still have good voltage withstand performance even after omitting the GaN high-resistivity layer, avoiding breakdown and leakage under high voltage. It also significantly improves the heat dissipation performance of the GaN epitaxial structure, which is beneficial for the efficient use of the device. Specifically, the breakdown voltage of the GaN epitaxial structure provided by this invention is ≥665.2V and the thermal resistance is ≤3.47K / W. In the preferred embodiment, the breakdown voltage is ≥726.6V and the thermal resistance is ≤2.30K / W.

[0040] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0041] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0042] Currently, in the process of SiC-based GaN epitaxial growth, it is necessary to grow an Fe-doped GaN high-resistivity layer to prevent leakage current and achieve high breakdown voltage in the resulting epitaxial structure. However, the growth of the Fe-GaN layer results in Fe memory contamination, with Fe residue remaining in the cavity. Furthermore, GaN has low thermal conductivity, and the high-resistivity Fe-GaN layer has high thermal resistance, leading to poor heat dissipation performance of the epitaxial structure. This results in excessively high junction temperatures, affecting device performance and reliability. Therefore, this invention optimizes the SiC-based GaN epitaxial structure by adjusting the substrate to a Fe-doped SiC semi-insulating substrate. This eliminates the need for a high-resistivity layer, enabling the resulting epitaxial structure to prevent leakage current and achieve high breakdown voltage while also providing good heat dissipation. Specifically:

[0043] I. This embodiment provides a SiC-based GaN epitaxial structure, the SiC-based GaN epitaxial structure comprising:

[0044] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0045] The substrate includes: an Fe-doped SiC semi-insulating substrate.

[0046] The Fe doping concentration in the Fe-doped SiC semi-insulating substrate is 1 × 10⁻⁶. 16 -1×10 17 pcs / cm 3 For example, it could be 1×10 16 pcs / cm 3 2×10 16 pcs / cm 3 3×10 16 pcs / cm 3 4×10 16 pcs / cm 3 5×10 16 pcs / cm 3 6×10 16 pcs / cm 3 7×10 16 pcs / cm 3 8×10 16 pcs / cm 3 9×10 16 pcs / cm 3 Or 1×10 17 pcs / cm 3 The values ​​may include, but are not limited to, the listed values; other unlisted values ​​within this range also meet the requirements.

[0047] The resistivity of the Fe-doped SiC semi-insulating substrate is >1×10⁻⁶. 9 Ω·cm.

[0048] In this invention, the Fe-doped SiC semi-insulating substrate can be obtained according to conventional substrate preparation processes in the art. An exemplary preparation process is as follows: FeSi2 and SiC raw materials are uniformly mixed in a crucible. Under high temperature (>2100℃) and low pressure (<3mbar), the SiC raw material and FeSi2 raw materials sublimate together. On the seed crystal surface, the gaseous phase reaches supersaturation, and SiC and Fe atoms co-deposit and crystallize on the seed crystal. Fe atoms enter the SiC lattice, mainly occupying Si sites, forming deep-level acceptor centers. After growth, the temperature is slowly lowered to room temperature to obtain an Fe-doped SiC ingot. Subsequently, a series of standard wafer processing steps are performed: orientation, cutting, grinding, polishing, and cleaning, finally yielding the Fe-doped semi-insulating SiC substrate.

[0049] The thickness of the GaN channel layer is 50-200nm, for example, it can be 50nm, 65nm, 80nm, 95nm, 110nm, 125nm, 140nm, 155nm, 170nm, 185nm or 200nm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0050] The thickness of the AlN insertion layer is 1-1.5 nm, for example, it can be 1 nm, 1.05 nm, 1.1 nm, 1.15 nm, 1.2 nm, 1.25 nm, 1.3 nm, 1.35 nm, 1.4 nm, 1.45 nm or 1.5 nm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0051] The thickness of the AlGaN barrier layer is 20-30nm, for example, it can be 20nm, 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm or 30nm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0052] II. This embodiment provides a method for preparing a SiC-based GaN epitaxial structure, the method comprising:

[0053] GaN channel layer growth, AlN insertion layer growth, and AlGaN barrier layer growth were performed sequentially on a Fe-doped SiC semi-insulating substrate to obtain a SiC-based GaN epitaxial structure.

[0054] In this invention, the growth of each layer in the SiC-based GaN epitaxial structure is carried out by vapor deposition. Specifically, the carrier gas used can be nitrogen, hydrogen, or other commonly used carrier gases in the art; the Ga source can be TMGa, etc.; the nitrogen source can be ammonia, etc.; and the Al source can be TMAl, etc.

[0055] The flow rate of the carrier gas used in the growth of the GaN channel layer is 150-200 slm, for example, it can be 150 slm, 155 slm, 160 slm, 165 slm, 170 slm, 175 slm, 180 slm, 185 slm, 190 slm, 195 slm or 200 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0056] The flow rate of the Ga source used in the growth of the GaN channel layer is 200-300 sccm, for example, it can be 200 sccm, 210 sccm, 220 sccm, 230 sccm, 240 sccm, 250 sccm, 260 sccm, 270 sccm, 280 sccm, 290 sccm or 300 sccm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0057] The flow rate of the nitrogen source used in the GaN channel layer growth is 30-100 slm, for example, it can be 30 slm, 37 slm, 44 slm, 51 slm, 58 slm, 65 slm, 72 slm, 79 slm, 86 slm, 93 slm or 100 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0058] The growth temperature of the GaN channel layer is 1100-1120℃, for example, it can be 1100℃, 1102℃, 1104℃, 1106℃, 1108℃, 1110℃, 1112℃, 1114℃, 1116℃, 1118℃ or 1120℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0059] The growth pressure for growing the GaN channel layer is 100-200 mbar, for example, it can be 100 mbar, 110 mbar, 120 mbar, 130 mbar, 140 mbar, 150 mbar, 160 mbar, 170 mbar, 180 mbar, 190 mbar or 200 mbar, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0060] The flow rate of the carrier gas used in the growth of the AlN insertion layer is 50-100 slm, for example, it can be 50 slm, 55 slm, 60 slm, 65 slm, 70 slm, 75 slm, 80 slm, 85 slm, 90 slm, 95 slm or 100 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0061] The flow rate of the Al source used in the growth of the AlN insertion layer is 40-60 sccm, for example, it can be 40 sccm, 42 sccm, 44 sccm, 46 sccm, 48 sccm, 50 sccm, 52 sccm, 54 sccm, 56 sccm, 58 sccm or 60 sccm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0062] The flow rate of the nitrogen source used in the growth of the AlN insertion layer is 1-5 slm, for example, it can be 1 slm, 1.4 slm, 1.8 slm, 2.2 slm, 2.6 slm, 3 slm, 3.4 slm, 3.8 slm, 4.2 slm, 4.6 slm or 5 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0063] The growth temperature for the AlN insertion layer is 1100-1120℃, for example, it can be 1100℃, 1102℃, 1104℃, 1106℃, 1108℃, 1110℃, 1112℃, 1114℃, 1116℃, 1118℃ or 1120℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0064] The growth pressure for growing the AlN insertion layer is 100-200 mbar, for example, it can be 100 mbar, 110 mbar, 120 mbar, 130 mbar, 140 mbar, 150 mbar, 160 mbar, 170 mbar, 180 mbar, 190 mbar or 200 mbar, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0065] The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 50-100 slm, for example, it can be 50 slm, 55 slm, 60 slm, 65 slm, 70 slm, 75 slm, 80 slm, 85 slm, 90 slm, 95 slm or 100 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0066] The flux of the Ga source used in the growth of the AlGaN barrier layer is 50-100 sccm, for example, it can be 50 sccm, 55 sccm, 60 sccm, 65 sccm, 70 sccm, 75 sccm, 80 sccm, 85 sccm, 90 sccm, 95 sccm or 100 sccm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0067] The nitrogen source flux used in the growth of the AlGaN barrier layer is 1-5 slm, for example, it can be 1 slm, 1.4 slm, 1.8 slm, 2.2 slm, 2.6 slm, 3 slm, 3.4 slm, 3.8 slm, 4.2 slm, 4.6 slm or 5 slm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0068] The flux of the Al source used in the growth of the AlGaN barrier layer is 50-200 sccm, for example, it can be 50 sccm, 65 sccm, 80 sccm, 95 sccm, 110 sccm, 125 sccm, 140 sccm, 155 sccm, 170 sccm, 185 sccm or 200 sccm, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0069] The growth temperature of the AlGaN barrier layer is 1100-1120℃, for example, it can be 1100℃, 1102℃, 1104℃, 1106℃, 1108℃, 1110℃, 1112℃, 1114℃, 1116℃, 1118℃ or 1120℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0070] The growth pressure for growing the AlGaN barrier layer is 100-200 mbar, for example, it can be 100 mbar, 110 mbar, 120 mbar, 130 mbar, 140 mbar, 150 mbar, 160 mbar, 170 mbar, 180 mbar, 190 mbar or 200 mbar, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0071] III. This embodiment provides a device, which includes the SiC-based GaN epitaxial structure.

[0072] In this invention, the device may be selected as a radio frequency (RF) microwave device and / or a power electronic device.

[0073] IV. To illustrate the high efficiency achieved by the SiC-based GaN epitaxial structure provided by this invention, the following practical example is used for explanation:

[0074] Example 1

[0075] This embodiment provides a SiC-based GaN epitaxial structure, including:

[0076] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0077] The substrate includes: an Fe-doped SiC semi-insulating substrate; the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 1×10⁻⁶. 16 pcs / cm 3 The resistivity of the Fe-doped SiC semi-insulating substrate is 2 × 10⁻⁶. 9 Ω·cm;

[0078] The thickness of the GaN channel layer is 100 nm;

[0079] The thickness of the AlN insertion layer is 1.4 nm;

[0080] The thickness of the AlGaN barrier layer is 25 nm.

[0081] The preparation process is as follows:

[0082] GaN channel layer growth, AlN insertion layer growth and AlGaN barrier layer growth were performed sequentially on Fe-doped SiC semi-insulating substrate to obtain SiC-based GaN epitaxial structure.

[0083] The flow rate of the carrier gas used in the growth of the GaN channel layer is 180 slm, the flow rate of the Ga source is 250 sccm, the flow rate of the nitrogen source is 50 slm, the growth temperature is 1110℃, and the growth pressure is 150 mbar.

[0084] The flow rate of the carrier gas used in the growth of the AlN insertion layer is 60 slm, the flow rate of the Al source is 55 sccm, the flow rate of the nitrogen source is 3 slm, the growth temperature is 1110℃, and the growth pressure is 150 mbar.

[0085] The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 60 slm, the flow rate of the Ga source is 60 sccm, the flow rate of the nitrogen source is 3 slm, the flow rate of the Al source is 100 sccm, the growth temperature is 1110℃, and the growth pressure is 150 mbar.

[0086] The carrier gas used was nitrogen; the Ga source used was TMGa; the nitrogen source used was ammonia; and the Al source used was TMAl.

[0087] Example 2

[0088] This embodiment provides a SiC-based GaN epitaxial structure, including:

[0089] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0090] The substrate includes: an Fe-doped SiC semi-insulating substrate; the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 6 × 10⁻⁶. 17 pcs / cm 3 The resistivity of the Fe-doped SiC semi-insulating substrate is 3 × 10⁻⁶. 9 Ω·cm;

[0091] The thickness of the GaN channel layer is 150 nm;

[0092] The thickness of the AlN insertion layer is 1.2 nm;

[0093] The thickness of the AlGaN barrier layer is 28 nm.

[0094] The preparation process is as follows:

[0095] GaN channel layer growth, AlN insertion layer growth and AlGaN barrier layer growth were performed sequentially on Fe-doped SiC semi-insulating substrate to obtain SiC-based GaN epitaxial structure.

[0096] The flow rate of the carrier gas used in the growth of the GaN channel layer is 160 slm, the flow rate of the Ga source is 280 sccm, the flow rate of the nitrogen source is 80 slm, the growth temperature is 1115℃, and the growth pressure is 180 mbar.

[0097] The flow rate of the carrier gas used in the growth of the AlN insertion layer is 80 slm, the flow rate of the Al source is 50 sccm, the flow rate of the nitrogen source is 4 slm, the growth temperature is 1115℃, and the growth pressure is 180 mbar.

[0098] The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 80 slm, the flow rate of the Ga source is 80 sccm, the flow rate of the nitrogen source is 4 slm, the flow rate of the Al source is 150 sccm, the growth temperature is 1115℃, and the growth pressure is 180 mbar.

[0099] The carrier gas used was nitrogen; the Ga source used was TMGa; the nitrogen source used was ammonia; and the Al source used was TMAl.

[0100] Example 3

[0101] This embodiment provides a SiC-based GaN epitaxial structure, including:

[0102] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0103] The substrate includes: an Fe-doped SiC semi-insulating substrate; the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 5 × 10⁻⁶. 17 pcs / cm 3 The resistivity of the Fe-doped SiC semi-insulating substrate is 2.5 × 10⁻⁶. 9 Ω·cm;

[0104] The thickness of the GaN channel layer is 200 nm;

[0105] The thickness of the AlN insertion layer is 1 nm;

[0106] The thickness of the AlGaN barrier layer is 30 nm.

[0107] The preparation process is as follows:

[0108] GaN channel layer growth, AlN insertion layer growth and AlGaN barrier layer growth were performed sequentially on Fe-doped SiC semi-insulating substrate to obtain SiC-based GaN epitaxial structure.

[0109] The flow rate of the carrier gas used in the growth of the GaN channel layer is 200 slm, the flow rate of the Ga source is 300 sccm, the flow rate of the nitrogen source is 100 slm, the growth temperature is 1120℃, and the growth pressure is 100 mbar.

[0110] The flow rate of the carrier gas used in the growth of the AlN insertion layer is 100 slm, the flow rate of the Al source is 60 sccm, the flow rate of the nitrogen source is 5 slm, the growth temperature is 1120℃, and the growth pressure is 100 mbar.

[0111] The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 100 slm, the flow rate of the Ga source is 100 sccm, the flow rate of the nitrogen source is 5 slm, the flow rate of the Al source is 200 sccm, the growth temperature is 1120℃, and the growth pressure is 100 mbar.

[0112] The carrier gas used was nitrogen; the Ga source used was TMGa; the nitrogen source used was ammonia; and the Al source used was TMAl.

[0113] Example 4

[0114] This embodiment provides a SiC-based GaN epitaxial structure, including:

[0115] A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate;

[0116] The substrate includes: an Fe-doped SiC semi-insulating substrate; the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 1×10⁻⁶. 17 pcs / cm 3 The resistivity of the Fe-doped SiC semi-insulating substrate is 5 × 10⁻⁶. 9 Ω·cm;

[0117] The thickness of the GaN channel layer is 50 nm;

[0118] The thickness of the AlN insertion layer is 1.5 nm;

[0119] The thickness of the AlGaN barrier layer is 20 nm.

[0120] The preparation process is as follows:

[0121] GaN channel layer growth, AlN insertion layer growth and AlGaN barrier layer growth were performed sequentially on Fe-doped SiC semi-insulating substrate to obtain SiC-based GaN epitaxial structure.

[0122] The flow rate of the carrier gas used in the growth of the GaN channel layer is 150 slm, the flow rate of the Ga source is 200 sccm, the flow rate of the nitrogen source is 30 slm, the growth temperature is 1100℃, and the growth pressure is 200 mbar.

[0123] The flow rate of the carrier gas used in the growth of the AlN insertion layer is 50 slm, the flow rate of the Al source is 40 sccm, the flow rate of the nitrogen source is 1 slm, the growth temperature is 1100℃, and the growth pressure is 200 mbar.

[0124] The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 50 slm, the flow rate of the Ga source is 50 sccm, the flow rate of the nitrogen source is 1 slm, the flow rate of the Al source is 50 sccm, the growth temperature is 1100℃, and the growth pressure is 200 mbar.

[0125] The carrier gas used was nitrogen; the Ga source used was TMGa; the nitrogen source used was ammonia; and the Al source used was TMAl.

[0126] Example 5

[0127] The only difference from Example 1 is that the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 0.5 × 10⁻⁶. 16 pcs / cm 3 .

[0128] Example 6

[0129] The only difference from Example 1 is that the Fe doping amount in the Fe-doped SiC semi-insulating substrate is 2 × 10⁻⁶. 17 pcs / cm 3 .

[0130] Comparative Example 1

[0131] The only difference from Example 1 is that the Fe-doped SiC semi-insulating substrate is replaced with a SiC substrate.

[0132] Comparative Example 2

[0133] The only difference from Example 1 is that the doping element in the Fe-SiC semi-insulating substrate is replaced with an equal amount of Mn.

[0134] Comparative Example 3

[0135] The only difference from Example 1 is that the doping element in the Fe-SiC semi-insulating substrate is replaced with an equal amount of Cr.

[0136] Comparative Example 4

[0137] The only difference from Example 1 is that the doping elements in the Fe-SiC semi-insulating substrate are replaced with an equal amount of Ge.

[0138] Comparative Example 5

[0139] The only difference from Example 1 is that the doping element in the Fe-SiC semi-insulating substrate is replaced with an equal amount of Mg.

[0140] Comparative Example 6

[0141] The only difference from Example 1 is that the doping elements in the Fe-SiC semi-insulating substrate are replaced with an equal amount of V.

[0142] Comparative Example 7

[0143] The only difference from Example 1 is that the doping elements in the Fe-SiC semi-insulating substrate are replaced with an equal amount of O.

[0144] Comparative Example 8

[0145] The only difference from Example 1 is that the substrate is replaced with a SiC substrate, and a GaN high-resistivity layer is formed between the GaN channel layer and the substrate. The Fe doping amount in the GaN high-resistivity layer remains unchanged at 1×10⁻⁶. 16 pcs / cm 3 The thickness of the high-resistivity layer is 2.5 μm.

[0146] The SiC-based GaN epitaxial structures obtained in the above embodiments and comparative examples were subjected to voltage withstand performance and heat dissipation performance tests. The voltage withstand performance was characterized by testing the breakdown voltage according to GB / T 29332-2012, and the heat dissipation performance was characterized by testing the thermal resistance according to GB / T 14862-1993, the test method for junction-to-case thermal resistance of semiconductor integrated circuit packages. The results are detailed in Table 1.

[0147] Table 1

[0148]

[0149] As shown in Table 1, the SiC-based GaN epitaxial structure provided by the present invention optimizes the SiC-based GaN epitaxial structure by doping Fe into the substrate to make the substrate a semi-insulating substrate, thus eliminating the need for a high-resistivity layer. This allows the resulting epitaxial structure to avoid leakage current and breakdown at high voltage, while also possessing a high breakdown voltage and good heat dissipation.

[0150] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0151] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0152] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A SiC-based GaN epitaxial structure, characterized in that, The SiC-based GaN epitaxial structure includes: A GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer are sequentially disposed on a substrate; The substrate includes: an Fe-doped SiC semi-insulating substrate.

2. The SiC-based GaN epitaxial structure as described in claim 1, characterized in that, The Fe doping concentration in the Fe-doped SiC semi-insulating substrate is 1×10⁻⁶. 16 -1×10 17 pcs / cm 3 ; Preferably, the resistivity of the Fe-doped SiC semi-insulating substrate is >1×10⁻⁶. 9 Ω·cm.

3. The SiC-based GaN epitaxial structure as described in claim 1, characterized in that, The thickness of the GaN channel layer is 50-200 nm; Preferably, the thickness of the AlN insertion layer is 1-1.5 nm; Preferably, the thickness of the AlGaN barrier layer is 20-30 nm.

4. A method for preparing a SiC-based GaN epitaxial structure as described in any one of claims 1-3, characterized in that, The preparation method includes: GaN channel layer growth, AlN insertion layer growth, and AlGaN barrier layer growth were performed sequentially on a Fe-doped SiC semi-insulating substrate to obtain a SiC-based GaN epitaxial structure.

5. The preparation method according to claim 4, characterized in that, The flow rate of the carrier gas used in the growth of the GaN channel layer is 150-200 slm; Preferably, the flow rate of the Ga source used in the growth of the GaN channel layer is 200-300 sccm; Preferably, the flow rate of the nitrogen source used in the GaN channel layer growth is 30-100 slm.

6. The preparation method according to claim 4, characterized in that, The growth temperature for the GaN channel layer is 1100-1120℃; Preferably, the growth pressure for growing the GaN channel layer is 100-200 mbar.

7. The preparation method according to claim 4, characterized in that, The flow rate of the carrier gas used in the growth of the AlN insertion layer is 50-100 slm; Preferably, the flow rate of the Al source used in the growth of the AlN insertion layer is 40-60 sccm; Preferably, the flow rate of the nitrogen source used in the growth of the AlN insertion layer is 1-5 slm.

8. The preparation method according to claim 4, characterized in that, The growth temperature for the AlN insertion layer is 1100-1120℃; Preferably, the growth pressure for growing the AlN insertion layer is 100-200 mbar.

9. The preparation method according to claim 4, characterized in that, The flow rate of the carrier gas used in the growth of the AlGaN barrier layer is 50-100 slm. Preferably, the flow rate of the Ga source used in the growth of the AlGaN barrier layer is 50-100 sccm; Preferably, the flow rate of the nitrogen source used in the growth of the AlGaN barrier layer is 1-5 slm; Preferably, the flux of the Al source used in the growth of the AlGaN barrier layer is 50-200 sccm; Preferably, the growth temperature of the AlGaN barrier layer is 1100-1120℃; Preferably, the growth pressure for growing the AlGaN barrier layer is 100-200 mbar.

10. A device, characterized in that, The device includes: a SiC-based GaN epitaxial structure as described in any one of claims 1-3.

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