Improved high-resistivity transistor epitaxial wafers and their fabrication methods

Abstract

This disclosure provides an improved high-resistivity transistor epitaxial wafer and its fabrication method, belonging to the field of semiconductor device technology. The high-resistivity layer in the high-electron-mobility transistor epitaxial wafer is replaced with a composite high-resistivity layer, which comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially. Both the first and second AlGaN sublayers are doped with carbon. This reduces the possibility of leakage current caused by impurities and two-dimensional electron gases. The AlN and InGaN sublayers block the diffusion of impurities and two-dimensional electron gases from the substrate, improving the crystal quality of the channel layer and reducing leakage current in the AlGaN buffer layer. The high-resistivity effect and the performance and reliability of the high-electron-mobility transistor are thus improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor device technology, and in particular to a high electron mobility transistor epitaxial wafer with improved high resistivity layer and its fabrication method. Background Technology

[0002] HEMT (High Electron Mobility Transistor) is a heterojunction field-effect transistor widely used in various electrical appliances. HEMT epitaxial wafers are the foundation for fabricating HEMT devices. An HEMT epitaxial wafer consists of a substrate and sequentially stacked layers on the substrate: an AlN layer, an AlGaN buffer layer, a GaN high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer.

[0003] HEMT epitaxial wafers are often grown using silicon substrates. However, oxygen atoms released from the decomposition of oxides (such as SiO2) on the silicon substrate surface at high temperatures diffuse into the AlGaN buffer layer and GaN high-resistivity layer during epitaxial growth. This causes leakage current in the AlGaN buffer layer and GaN high-resistivity layer, preventing the achievement of high resistance and resulting in reduced device performance. Furthermore, the high concentration of two-dimensional electron gas near the channel layer makes it easy for electrons to overflow into the buffer layer and GaN high-resistivity layer, which also leads to the inability to achieve high resistance. Consequently, the performance and reliability of the resulting high electron mobility transistors are not ideal. Summary of the Invention

[0004] This disclosure provides an improved high-electron-mobility transistor epitaxial wafer with an improved high-resistivity layer and its fabrication method, which can improve the performance and reliability of high-electron-mobility transistors. The technical solution is as follows:

[0005] This disclosure provides a high electron mobility transistor epitaxial wafer, wherein the high electron mobility transistor epitaxial wafer with improved high resistivity layer includes a silicon substrate and an AlN layer, an AlGaN buffer layer, a composite high resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer sequentially stacked on the silicon substrate.

[0006] The composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially, wherein both the first AlGaN sublayer and the second AlGaN sublayer are doped with carbon.

[0007] Optionally, the thickness of the AlN sublayer and the thickness of the InGaN sublayer are both less than the thickness of the first AlGaN sublayer.

[0008] Optionally, the thickness of the AlN sublayer is equal to the thickness of the InGaN sublayer.

[0009] Optionally, the thickness of the AlN sublayer and the InGaN sublayer both range from 50 to 100 nm.

[0010] Optionally, the In composition of the InGaN sublayer is 0.1 to 0.5.

[0011] Optionally, the thickness of the first AlGaN sublayer is equal to the thickness of the second AlGaN sublayer.

[0012] Optionally, the concentration of carbon doped in the first AlGaN sublayer is equal to the concentration of carbon doped in the second AlGaN sublayer.

[0013] Optionally, the carbon concentration in the first AlGaN sublayer is 10. 19 cm -3 ~10 20 cm -3 .

[0014] This disclosure provides a method for fabricating a high-electron-mobility transistor epitaxial wafer with an improved high-resistivity layer. The method includes:

[0015] Provide a silicon substrate;

[0016] An AlN layer, an AlGaN buffer layer, a composite high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer are sequentially grown on the silicon substrate.

[0017] The composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially, wherein both the first AlGaN sublayer and the second AlGaN sublayer are doped with carbon.

[0018] Optionally, the method for fabricating the high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer includes:

[0019] The growth temperature of the InGaN sublayer is 200-300°C lower than that of the first AlGaN sublayer.

[0020] The beneficial effects of the technical solutions provided in this disclosure include:

[0021] The high-resistivity layer in the epitaxial wafer of a high-electron-mobility transistor is replaced with a composite high-resistivity layer. This composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially. Both the first and second AlGaN sublayers are doped with carbon. The carbon doping in both the first and second AlGaN sublayers improves their high-resistivity performance and reduces the possibility of leakage caused by impurities and two-dimensional electron gases. The AlN and InGaN sublayers between the first and second AlGaN sublayers form a high-barrier layer. The high-barrier AlN sublayer blocks impurities diffusing upwards from the silicon substrate, preventing them from diffusing into the channel layer and affecting the crystal quality of the epitaxial layer. It also blocks the two-dimensional electron gas from the channel layer from diffusing further into the AlGaN buffer layer, preventing leakage in the AlGaN buffer layer. This achieves high resistance and improves the crystal quality of the channel layer. After the AlN sublayer blocks most of the impurities, the low-barrier InGaN sublayer can confine fewer impurities diffusing upward from the silicon substrate, preventing them from diffusing into the channel layer and affecting the crystal quality of the epitaxial layer. Similarly, it can also confine most of the two-dimensional electron gas from the channel layer to continue diffusing into the AlGaN buffer layer, preventing leakage current in the AlGaN buffer layer. This achieves high resistance, which not only improves the crystal quality of the channel layer but also reduces the leakage current of the AlGaN buffer layer. The overall quality of the high-resistivity and high-electron-mobility transistor is effectively improved, ultimately enhancing the pinch-off characteristics and breakdown voltage characteristics of the device. The performance and reliability of the high-resistivity and high-electron-mobility transistor are also improved. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a high electron mobility transistor epitaxial wafer with an improved high resistivity layer provided in an embodiment of this disclosure;

[0024] Figure 2 This is a schematic diagram of another high electron mobility transistor epitaxial wafer with improved high resistivity layer provided by an embodiment of this disclosure;

[0025] Figure 3 This is a flowchart of a method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer provided by an embodiment of this disclosure;

[0026] Figure 4This is a flowchart of another method for fabricating high electron mobility transistor epitaxial wafers with improved high resistivity layers provided in this disclosure. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of a high electron mobility transistor epitaxial wafer with improved high resistivity layer provided in an embodiment of this disclosure, with reference to... Figure 1 As can be seen, the present disclosure provides a high electron mobility transistor epitaxial wafer. The high electron mobility transistor epitaxial wafer with improved high resistivity layer includes a silicon substrate 1 and an AlN layer 2, an AlGaN buffer layer 3, a composite high resistivity layer 4, a GaN channel layer 5, an AlGaN barrier layer 6 and a GaN capping layer 7 sequentially stacked on the silicon substrate 1.

[0029] The composite high-resistivity layer 4 includes a first AlGaN sublayer 41, an AlN sublayer 42, an InGaN sublayer 43, and a second AlGaN sublayer 44 stacked sequentially. Both the first AlGaN sublayer 41 and the second AlGaN sublayer 44 are doped with carbon.

[0030] The high-resistivity layer in the high electron mobility transistor epitaxial wafer is replaced with a composite high-resistivity layer 4. This composite high-resistivity layer 4 comprises a first AlGaN sublayer 41, an AlN sublayer 42, an InGaN sublayer 43, and a second AlGaN sublayer 44, stacked sequentially. Both the first AlGaN sublayer 41 and the second AlGaN sublayer 44 are doped with carbon. The carbon doping in both the first AlGaN sublayer 41 and the second AlGaN sublayer 44 improves their high-resistivity performance and reduces the possibility of leakage current caused by impurities and two-dimensional electron gas. The AlN sublayer 42 and InGaN sublayer 43 between the first AlGaN sublayer 41 and the second AlGaN sublayer 44 have a high barrier. The high barrier AlN sublayer 42 can block impurities from diffusing upward from the silicon substrate 1, preventing them from diffusing into the channel layer 5 and affecting the crystal quality of the epitaxial layer. It can also block the two-dimensional electron gas from the channel layer 5 from continuing to diffuse into the AlGaN buffer layer 3, preventing leakage of the AlGaN buffer layer 3, thereby achieving high resistance and improving the crystal quality of the channel layer 5. After the AlN sublayer 42 blocks most of the impurities, the low-barrier InGaN sublayer 43 can confine fewer impurities diffusing upward from the silicon substrate 1, preventing them from diffusing into the channel layer 5 and affecting the crystal quality of the epitaxial layer. Similarly, it can also confine most of the two-dimensional electron gas from the channel layer 5 to continue diffusing into the AlGaN buffer layer 3, preventing leakage in the AlGaN buffer layer 3, thereby achieving high resistance. This not only improves the crystal quality of the channel layer 5 but also reduces the leakage of the AlGaN buffer layer 3. The overall quality of the high-resistivity and high-electron-mobility transistor is effectively improved, ultimately enhancing the pinch-off characteristics and breakdown voltage characteristics of the device. The performance and reliability of the high-resistivity and high-electron-mobility transistor are also improved.

[0031] Optionally, the overall thickness of the composite high-resistivity layer 4 is 0.8 to 2 micrometers.

[0032] The overall thickness of the composite high-resistivity layer 4 is within the above range. The composite high-resistivity layer 4 can achieve a good high-resistivity effect, and the quality of the composite high-resistivity layer 4 itself is also good, which can improve the quality of the final high electron mobility transistor.

[0033] For example, the thickness of the AlN sublayer 42 and the thickness of the InGaN sublayer 43 are both less than the thickness of the first AlGaN sublayer 41.

[0034] The thicknesses of both the AlN sublayer 42 and the InGaN sublayer 43 are smaller than the thickness of the first AlGaN sublayer 41. While the first AlGaN sublayer 41 provides a certain high resistivity, it can also reduce the thicknesses of the AlN sublayer 42 and the InGaN sublayer 43 to some extent. This ensures stable improvement in impurities and high resistivity while reducing the fabrication cost of the composite high-resistivity layer 4, thus guaranteeing a high-quality high-electron-mobility transistor at a reasonable cost.

[0035] Optionally, the thickness of both the AlN sublayer 42 and the InGaN sublayer 43 is less than the thickness of the second AlGaN sublayer 44. The InGaN sublayer 43 can stably transition to the subsequent channel layer 5 through the second AlGaN sublayer 44, and can also effectively isolate the two-dimensional electron gas.

[0036] Optionally, the thickness of the AlN sublayer 42 is equal to the thickness of the InGaN sublayer 43.

[0037] The thickness of the AlN sublayer 42 is equal to that of the InGaN sublayer 43, which can effectively block and confine impurities, thereby improving the quality of the composite high-resistivity layer 4. Furthermore, the overall fabrication cost is reasonable and will not be excessive.

[0038] Optionally, the thickness of the AlN sublayer 42 and the InGaN sublayer 43 are both in the range of 50–100 nm.

[0039] The thicknesses of AlN sublayer 42 and InGaN sublayer 43 are both within the above range, which ensures that the quality of the resulting composite high-resistivity layer 4 is good, effectively improving the final high electron mobility transistor, and the overall fabrication cost of the composite high-resistivity layer 4 is also reasonable.

[0040] For example, the In composition of the InGaN sublayer 43 is 0.1 to 0.5.

[0041] The In composition of the InGaN sublayer 43 is within the above range, the lattice mismatch between the InGaN sublayer 43 and the AlN sublayer 42 is relatively small, and the quality of the composite high-resistivity layer 4 itself is good. Furthermore, the barrier of the InGaN sublayer 43 is sufficient to confine impurities, effectively preventing impurities from entering the subsequent epitaxial structure and affecting the high electron mobility transistor, thus effectively improving the quality and performance of the final high electron mobility transistor.

[0042] Optionally, the thickness of the first AlGaN sublayer 41 is equal to the thickness of the second AlGaN sublayer 44.

[0043] The thickness of the first AlGaN sublayer 41 is equal to the thickness of the second AlGaN sublayer 44, which facilitates fabrication and ensures a good overall high-resistivity effect, thereby improving the quality and performance of the final high-electron-mobility transistor.

[0044] For example, the thickness of the first AlGaN sublayer 41 and the thickness of the second AlGaN sublayer 44 range from 0.5 to 1.0 micrometers.

[0045] The thicknesses of the first AlGaN sublayer 41 and the second AlGaN sublayer 44 are within the ranges described above. This ensures the binding effect of the first AlGaN sublayer 41 and the second AlGaN sublayer 44 on impurities and guarantees a good transition and fit between the composite high-resistivity layer 4 and other epitaxial materials. This effectively improves the quality and performance of the final high-electron-mobility transistor.

[0046] Optionally, the concentration of carbon doped in the first AlGaN sublayer 41 is equal to the concentration of carbon doped in the second AlGaN sublayer 44.

[0047] Both the first AlGaN sublayer 41 and the second AlGaN sublayer 44 are doped with carbon, which can improve the high resistivity performance of the first AlGaN sublayer 41 and the second AlGaN sublayer 44. The carbon doping concentration in the first AlGaN sublayer 41 and the second AlGaN sublayer 44 is equal, which can facilitate the preparation of the first AlGaN sublayer 41 and the second AlGaN sublayer 44. The preparation cost of the first AlGaN sublayer 41 and the second AlGaN sublayer 44 can be reasonably controlled to ensure the quality of the final high electron mobility transistor while controlling the preparation cost of the high electron mobility transistor.

[0048] Optionally, the carbon concentration in the first AlGaN sublayer 41 is 10. 19 cm -3 ~10 20 cm -3 .

[0049] It can ensure the quality of the first AlGaN sublayer 41 itself while effectively improving the high resistance performance of the first AlGaN sublayer 41.

[0050] It should be noted that the carbon doping concentration in the second AlGaN sublayer 44 can also be within the above range.

[0051] Figure 2 This is a schematic diagram of another high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer provided in this disclosure embodiment, with reference to... Figure 2It is known that the high electron mobility transistor epitaxial wafer may include a substrate 1 and an AlN layer 2, an AlGaN buffer layer 3, a composite high resistivity layer 4, a GaN channel layer 5, an AlN insertion layer 8, an AlGaN barrier layer 6, and a GaN capping layer 7 sequentially stacked on the silicon substrate 1.

[0052] It should be noted that, Figure 2 The structure of the composite high-resistivity layer 4 shown is similar to Figure 1 The structure of the composite high-resistivity layer 4 shown is the same, so it will not be described again here.

[0053] Optionally, the thickness of AlN layer 2 is 150–300 nm. This ensures good quality of AlN layer 2, providing a good growth foundation for HEMT epitaxial wafers.

[0054] For example, the thickness of the AlGaN buffer layer 3 is 1 to 1.5 micrometers. The resulting AlGaN buffer layer 3 has good quality.

[0055] Optionally, the thickness of the GaN channel layer 5 can be 100–400 nm.

[0056] The thickness of the GaN channel layer 5 is appropriate, and while the cost is reasonable, it can effectively improve the quality of high electron mobility transistor epitaxial wafers.

[0057] In one implementation provided in this disclosure, the thickness of the GaN channel layer 5 can be 400 nm. This disclosure does not impose any limitation on this.

[0058] Figure 2 relative to Figure 1 The structure of the HEMT epitaxial wafer incorporates an AlN insertion layer 8. This reduces the negative impact of lattice mismatch in the underlying layer. Furthermore, the interfaces between the AlN insertion layer 8 and the GaN channel layer 5, as well as between the AlN insertion layer 8 and the AlGaN barrier layer 6, form two-dimensional electron gases. These two-dimensional electron gases increase carrier accumulation at the interfaces, ensuring the effective use of the high electron mobility transistor epitaxial wafer.

[0059] Optionally, the thickness of the AlN insertion layer 8 is 0.5–2 nm.

[0060] The thickness of the AlN insertion layer 8 within the above range can effectively form a two-dimensional electron gas without significantly increasing the cost.

[0061] In one implementation provided in this disclosure, the thickness of the AlN insertion layer 8 can be 2 nm. This disclosure does not impose any limitation on this.

[0062] Optionally, the thickness of the AlGaN barrier layer 6 can be 15–40 nm. This ensures the quality of the high electron mobility transistor epitaxial wafer.

[0063] In one implementation provided in this disclosure, the thickness of the AlGaN barrier layer 6 can be 100 nm. This disclosure does not impose any limitation on this.

[0064] For example, the GaN capping layer can be a P-type GaN layer, which facilitates fabrication and acquisition.

[0065] Optionally, the thickness of the GaN capping layer is 3–10 nm. The resulting GaN capping layer has good overall quality.

[0066] For example, the impurity within the GaN capping layer is Mg. This facilitates preparation and acquisition.

[0067] It should be noted that, Figure 2 This is merely one implementation of a high electron mobility transistor epitaxial wafer provided in this disclosure. In other implementations provided in this disclosure, the high electron mobility transistor epitaxial wafer may also be other forms of high electron mobility transistor epitaxial wafer including a reflective layer, and this disclosure does not impose any limitations on this.

[0068] Figure 3 This is a flowchart illustrating a method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer, provided in an embodiment of this disclosure. (Refer to...) Figure 3 As can be seen, this disclosure provides a method for fabricating a high-electron-mobility transistor epitaxial wafer with an improved high-resistivity layer. The method includes:

[0069] S101: Provides a silicon substrate.

[0070] S102: An AlN layer, an AlGaN buffer layer, a composite high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer are sequentially grown on a silicon substrate. The composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially. Both the first AlGaN sublayer and the second AlGaN sublayer are doped with carbon.

[0071] Figure 3 The technical effects of the preparation method shown can be referred to Figure 1 The technical effects corresponding to the structure of the high electron mobility transistor epitaxial wafer shown are not elaborated here.

[0072] For example, in step S102, the growth temperature of the InGaN sublayer is 200-300°C lower than that of the first AlGaN sublayer.

[0073] The growth temperature of the InGaN sublayer is 200-300℃ lower than that of the first AlGaN sublayer. This ensures that the InGaN sublayer grows more densely and reduces the possibility of In precipitation in the InGaN sublayer, thus effectively improving the quality of the obtained InGaN sublayer.

[0074] Optionally, the growth temperature of the AlN sublayer can be the same as that of the InGaN sublayer.

[0075] It can ensure the quality of the InGaN sublayer grown on the AlN sublayer. When growing the InGaN sublayer after growing the AlN sublayer, there is no need to adjust the growth temperature of the epitaxial growth equipment. It can ensure the quality of the composite high resistivity layer while improving the growth efficiency of the composite high resistivity layer.

[0076] Optionally, in step S102, the growth conditions for the composite high-resistivity layer further include:

[0077] The growth temperatures of the first AlGaN sublayer, the AlN sublayer, and the second AlGaN sublayer can be 1000–1200℃, 800–1000℃, and 1000–1200℃, respectively.

[0078] This ensures that the resulting composite high-resistivity layer is of good quality.

[0079] For example, the growth temperature of the first AlGaN sublayer is the same as that of the second AlGaN sublayer. This facilitates the fabrication of the composite high-resistivity layer and controls its fabrication cost.

[0080] Optionally, the growth pressure of the composite high-resistivity layer can be 40–70 mbar. This ensures the growth quality of the composite high-resistivity layer.

[0081] Figure 4 This is a flowchart of another method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer provided by embodiments of this disclosure. The method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer may further include:

[0082] S201: Provides a silicon substrate.

[0083] S202 pre-deposits a layer of Al atoms on a silicon substrate.

[0084] Because Al atoms have relatively low lateral mobility, pre-laying an Al atom layer helps improve the flatness of the subsequent first AlN layer, thereby improving the uniformity of the entire epitaxial layer. This is beneficial for improving the overall quality of HEMT epitaxial wafers.

[0085] Optionally, an Al source with a flow rate of 50-200 sccm is pre-introduced into the reaction chamber for 10-100 seconds at a temperature of 1000-1100℃ to deposit an Al atomic layer on the substrate.

[0086] Under the above temperature conditions, an Al source with a flow rate of 50-200 sccm is introduced into the reaction chamber for a certain period of time, which can stack a relatively stable Al atomic layer with a suitable thickness on the substrate, ensuring the stable and uniform growth of the subsequent AlN layer.

[0087] S203: An AlN layer is grown on the substrate.

[0088] Optionally, the growth temperature of the AlN layer can be 1000–1100℃, which can yield AlN layers of good quality.

[0089] S204: An AlGaN buffer layer is grown on an AlN layer.

[0090] Optionally, step S204 may include: introducing an Al source, a Ga source, and a reaction gas into the reaction chamber using argon as a carrier gas to grow an AlGaN film; turning off the Al source, the Ga source, and the reaction gas; introducing hydrogen into the reaction chamber at a temperature of 1050–1250°C to treat the AlGaN film; and repeating the above steps until an AlGaN layer is obtained.

[0091] During the growth of the AlGaN buffer layer, the same growth method as the second AlN layer is adopted. This can improve the growth uniformity and surface flatness of the AlGaN buffer layer. While improving the crystal quality of the AlGaN buffer layer itself, it can also improve the structure of gallium nitride and other structures grown on the surface of the AlGaN buffer layer.

[0092] Optionally, the thickness of the AlGaN film is 20–50 nm.

[0093] With the thickness of each AlGaN film within the above range, the growth of the AlGaN film can be more uniform, and the surface flatness of the AlGaN film is higher. Combined with subsequent hydrogen treatment, the surface dislocation density of the AlGaN film can be effectively reduced, thereby improving the crystal quality of the final second AlGaN layer.

[0094] Optionally, the AlGaN film is treated by introducing hydrogen gas into the reaction chamber at a temperature of 1050–1250 °C for 5–10 seconds.

[0095] Within the above range, the hydrogen treatment time ensures that the surface of the AlGaN film is adequately treated by the hydrogen, and the AlGaN film undergoes sufficient annealing during this time, which further improves the crystal quality of the AlGaN film.

[0096] Optionally, the thickness of the AlGaN buffer layer is 100–200 nm.

[0097] When the thickness of the AlGaN buffer layer is within the above range, the quality of the AlGaN buffer layer is good, and it can also provide a good growth foundation for subsequent growth structures.

[0098] Optionally, using argon as a carrier gas to introduce Al source, Ga source, and reactant gas into the reaction chamber to grow an AlGaN film, the method further includes:

[0099] Argon gas was used as a carrier gas to introduce Al source, Ga source, Fe source and reaction gas into the reaction chamber to grow AlGaN film.

[0100] The incorporation of Fe into the AlGaN film can achieve high resistance in the AlGaN buffer layer, facilitating the transition to subsequent high-resistivity gallium nitride materials.

[0101] It should be noted that, assuming argon is used as the carrier gas to introduce Al, Ga, and Fe sources and reactants to grow the AlGaN film, the Al, Ga, and Fe sources and reactants must be shut off simultaneously during the subsequent hydrogen treatment of the AlGaN film.

[0102] Optionally, the flow rate of the Fe source is 50-200 sccm.

[0103] When the flow rate of the Fe source is within the above range, a high-quality AlGaN buffer layer can be obtained.

[0104] For example, the Fe doping concentration in the final AlGaN buffer layer is 10. 18 ~10 20 cm -3 The AlGaN buffer layer is of good quality and can achieve a good transition with subsequent high-resistivity gallium nitride materials.

[0105] Optionally, the growth conditions for the AlGaN buffer layer include a growth temperature of 1050℃ to 1250℃ and a pressure of 40 to 70 mbar. This can yield an AlGaN buffer layer of relatively good quality.

[0106] S205: A composite high-resistivity layer is grown on an AlGaN buffer layer.

[0107] The growth conditions and parameters for composite high-resistivity layers can be found by referring to [reference needed]. Figure 3 Step S102, as shown in the diagram, will not be repeated here.

[0108] S206: GaN channel layer is grown on a composite high resistivity layer.

[0109] Optionally, the growth conditions for the GaN channel layer include a growth temperature of 1050℃ to 1150℃ and a pressure of 150 to 250 mbar. This can yield a GaN channel layer of relatively good quality.

[0110] For example, the thickness of the GaN channel layer is between 1.0 and 1.5 micrometers. This improves the quality of the final HEMT epitaxial wafer. The resulting GaN channel layer has good quality.

[0111] S207: An AlN insertion layer is grown on a GaN channel layer.

[0112] Optionally, the growth temperature of the AlN insertion layer is 1050℃~1150℃, and the growth pressure of the AlN insertion layer is 40~70mbar. This can yield AlN insertion layers of good quality.

[0113] S208: An AlGaN barrier layer is grown on an AlN insertion layer.

[0114] Optionally, the growth temperature of the AlGaN barrier layer is 1050℃~1150℃, and the growth pressure of the AlGaN barrier layer is 40~70mbar. The resulting AlGaN barrier layer has good quality.

[0115] In one implementation provided in this disclosure, the growth temperature of the AlGaN barrier layer can be 1020℃. This disclosure does not impose any limitation on this.

[0116] S209: A GaN capping layer is grown on an AlGaN barrier layer.

[0117] Optionally, the growth temperature of the GaN capping layer is 1050℃~1150℃, and the growth pressure of the AlGaN barrier layer is 40~70mbar. The resulting GaN capping layer has good quality.

[0118] It should be noted that in the embodiments disclosed herein, the LED growth method is achieved using VeecoK 465i or C4 or RB MOCVD (Metal-Organic Chemical Vapor Deposition) equipment. High-purity H2 (hydrogen), high-purity N2 (nitrogen), or a mixture of high-purity H2 and high-purity N2 are used as the carrier gas; high-purity NH3 is used as the N source; trimethylgallium (TMGa) and triethylgallium (TEGa) are used as gallium sources; trimethylindium (TMIn) is used as the indium source; silane (SiH4) is used as the N-type dopant; trimethylaluminum (TMAl) is used as the aluminum source; magnesium cerium styrene (CP2Mg) is used as the P-type dopant; and ferrocene (Cp2Fe) is used as the precursor for the iron (Fe) source.

[0119] The above is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A high-electron-mobility transistor epitaxial wafer with improved high-resistivity layers, characterized in that, The improved high-resistivity transistor epitaxial wafer includes a silicon substrate and, sequentially stacked on the silicon substrate, an AlN layer, an AlGaN buffer layer, a composite high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer. The composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially, wherein both the first AlGaN sublayer and the second AlGaN sublayer are doped with carbon. The overall thickness of the composite high-resistivity layer is 0.8–2 micrometers; The thickness of the AlN sublayer and the thickness of the InGaN sublayer are both less than the thickness of the second AlGaN sublayer; The thickness of the AlN sublayer and the thickness of the InGaN sublayer are both less than the thickness of the first AlGaN sublayer; The thickness of the AlN sublayer and the InGaN sublayer both range from 50 to 100 nm. The thickness of the GaN channel layer is 100–400 nm.

2. The high electron mobility transistor epitaxial wafer with improved high resistivity layer according to claim 1, characterized in that, The thickness of the AlN sublayer is equal to the thickness of the InGaN sublayer.

3. The high electron mobility transistor epitaxial wafer with improved high resistivity layer according to claim 1 or 2, characterized in that, The In composition of the InGaN sublayer is 0.1 to 0.

5.

4. The high electron mobility transistor epitaxial wafer with improved high resistivity layer according to claim 1 or 2, characterized in that, The thickness of the first AlGaN sublayer is equal to the thickness of the second AlGaN sublayer.

5. The high electron mobility transistor epitaxial wafer with improved high resistivity layer according to claim 1 or 2, characterized in that, The concentration of carbon doped in the first AlGaN sublayer is equal to the concentration of carbon doped in the second AlGaN sublayer.

6. The high electron mobility transistor epitaxial wafer with improved high resistivity layer according to claim 5, characterized in that, The carbon concentration in the first AlGaN sublayer is 10. 19 cm -3 ~10 20 cm -3 .

7. A method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer, characterized in that, The method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer includes: Provide a silicon substrate; An AlN layer, an AlGaN buffer layer, a composite high-resistivity layer, a GaN channel layer, an AlGaN barrier layer, and a GaN capping layer are sequentially grown on the silicon substrate. The composite high-resistivity layer comprises a first AlGaN sublayer, an AlN sublayer, an InGaN sublayer, and a second AlGaN sublayer stacked sequentially. Both the first AlGaN sublayer and the second AlGaN sublayer are doped with carbon. The overall thickness of the composite high-resistivity layer is 0.8–2 micrometers. The thickness of the AlN sublayer and the InGaN sublayer are both less than the thickness of the second AlGaN sublayer, and the thickness of the AlN sublayer and the InGaN sublayer are both less than the thickness of the first AlGaN sublayer. The thickness range of the AlN sublayer and the InGaN sublayer is 50–100 nm. The thickness of the GaN channel layer is 100–400 nm.

8. The method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer according to claim 7, characterized in that, The method for fabricating a high-electron-mobility transistor epitaxial wafer with improved high-resistivity layer includes: The growth temperature of the InGaN sublayer is 200-300°C lower than that of the first AlGaN sublayer.

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