Epitaxial structure of PHEMT device based on gallium nitride high-resistance layer

Abstract

The invention provides an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer, which relates to the technical field of semiconductors and comprises a substrate layer, a GaN buffer layer, a GaN high-resistance layer, a GaN channel layer, an InGaN barrier layer and a cap layer, the substrate layer, the GaN buffer layer, the GaN high-resistance layer, the GaN channel layer, the InGaN barrier layer and the cap layer are sequentially laminated; the GaN high-resistance layer is a C-doped GaN high-resistance layer, and the doping concentration of the C-doped GaN high-resistance layer changes in an inverted step mode in the direction from the GaN buffer layer to the GaN channel layer; the number of concentration steps of the C-doped GaN high-resistance layer accords with the resistance matching principle and the electric field uniform distribution principle. The C doping concentration adopts an inverted step change mode, the resistance matching is accurately adjusted and optimized according to the electric field distribution and the carrier demand, the leakage current is reduced, the stability and the performance of the device are improved, and the non-uniform performance caused by uniform doping is avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer. Background Art

[0002] The gallium nitride (GaN) high-resistance layer refers to a region in GaN-based materials that has a relatively high resistance by controlling the doping concentration. Generally, the GaN high-resistance layer is used to isolate and support the two-dimensional electron gas (2DEG) in the device. It has a low carrier concentration and a high resistance, which can reduce current leakage and improve the stability and performance of the device. A PHEMT (Pseudomorphic High Electron Mobility Transistor) is a highly efficient field-effect transistor that uses a heterostructure and is mainly used in high-frequency and high-power applications. The PHEMT device significantly improves the carrier mobility through the formation of a two-dimensional electron gas (2DEG), thereby enhancing the switching speed and operating efficiency of the device. It usually uses GaN as the substrate material and combines materials such as AlGaN or InGaN to form a barrier layer.

[0003] PHEMT devices play a very important role in modern electronics, especially in high-frequency and high-power applications, due to their excellent switching characteristics, high efficiency, and low power consumption. GaN-based PHEMT devices can support higher operating voltages and frequencies and are widely used in fields such as communication, radar, and satellite communication. Their high electron mobility enables the device to have a faster response speed and lower power loss in high-frequency applications. In addition, due to their excellent thermal management capabilities, PHEMT devices can also operate stably under high-power output and are key components for high-performance devices such as future wireless communication, power amplifiers, and radio frequency power amplifiers.

[0004] However, in the existing PHEMT devices based on gallium nitride high-resistance layers, the determination of the doping concentration in the gallium nitride high-resistance layer relies too much on the subjective experience obtained during the experiment to set the doping concentration and the doping method of setting the doping concentration to be uniform. The uniform doping method cannot be precisely adjusted according to the electric field distribution and carrier requirements, resulting in the same doping concentration throughout the GaN high-resistance layer, which cannot optimize the resistance matching and electric field distribution, easily leads to non-uniform device performance, increases the occurrence of leakage current and defects, and this subjective decision-making method often cannot balance the control among different device performance requirements, and is extremely likely to cause device defects. Summary of the Invention

[0005] In order to solve the problem that the existing PHEMT device based on gallium nitride high resistance layer, in the process of determining the doping concentration of the gallium nitride high resistance layer, relies too much on subjective experience obtained in the experimental process to set the doping concentration and sets the doping concentration to a uniform doping method, and the uniform doping method cannot be accurately adjusted according to the electric field distribution and carrier requirements, resulting in the doping concentration being the same in the entire GaN high resistance layer, and the resistance matching and electric field distribution cannot be optimized, which easily leads to uneven device performance, increased leakage current and the occurrence of defects, and this subjective decision-making method often cannot be balanced and controlled in different device performance requirements, which easily leads to device defects. The present invention provides an epitaxial structure of a PHEMT device based on a gallium nitride high resistance layer.

[0006] The technical solution provided by the embodiment of the present invention is as follows: In a first aspect, an embodiment of the present invention provides an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer, comprising a substrate layer, a GaN buffer layer, a GaN high-resistance layer, a GaN channel layer, an InGaN barrier layer and a cap layer; The substrate layer, the GaN buffer layer, the GaN high resistance layer, the GaN channel layer, the InGaN barrier layer and the cap layer are stacked in sequence; The GaN high resistance layer is a C-doped GaN high resistance layer, wherein the doping concentration of the C-doped GaN high resistance layer changes in an inverse step in the direction from the GaN buffer layer to the GaN channel layer; The number of concentration steps of the C-doped GaN high-resistance layer complies with the resistance matching principle and the electric field uniform distribution principle.

[0007] Optionally, the substrate layer includes a Si substrate and a sapphire substrate.

[0008] Optionally, it also includes: a source electrode, a drain electrode and a gate electrode; The source electrode is arranged in contact with the cap layer, and the source electrode and the drain electrode are arranged in contact with the InGaN barrier layer respectively.

[0009] Optionally, in combination with the constraint condition that the thermal resistance of the C-doped GaN high-resistance layer is less than a preset thermal resistance, a constraint condition for the thickness of the C-doped GaN high-resistance layer is determined, and the constraint condition is specifically: ; in, represents the thermal conductivity of GaN, represents the thermal resistance of the C-doped GaN high-resistance layer, Indicates the preset thermal resistance, represents the thickness of the C-doped GaN high-resistance layer, Indicates the breakdown voltage of the PHEMT device, Indicates the breakdown voltage threshold of the PHEMT device, Represents the critical breakdown electric field strength of GaN.

[0010] Optionally, based on the thickness of the C-doped GaN high-resistance layer that meets the constraint conditions, when the tunneling current density of the heterojunction formed by the GaN channel layer and the InGaN barrier layer is less than the preset tunneling current density, the maximum doping concentration of the C-doped GaN high-resistance layer is determined in combination with the carrier freeze model.

[0011] Optionally, the calculation method of the maximum doping concentration is specifically: ; Where, Represents the electron mobility of GaN at different C doping concentrations, Represents the maximum doping concentration, q represents the electron charge, Represents the resistivity of GaN at different C doping concentrations, Represents the tunneling current density, Represents the defect density of the C-doped GaN high-resistance layer, Represents related to The trap-assisted tunneling current, Represents the carrier diffusion current of the C-doped GaN high-resistance layer, Represents the effective Richardson constant reflecting the hot electron emission ability of C-doped GaN, Represents the barrier height of the InGaN barrier layer, e represents the natural constant, T represents the operating temperature of the PHEMT device, k represents the Boltzmann constant, Represents the preset tunneling current density, Represents the electron diffusion coefficient of GaN, Represents the dielectric constant of GaN, Represents the critical breakdown electric field strength of GaN, E t Represents the trap energy level depth of C-doped GaN, E represents the electric field strength borne by the C-doped GaN high-resistance layer in the PHEMT device, π represents the pi, Represents related to The electron diffusion coefficient,

[0012] Optionally, the calculation formula of the number of concentration steps is specifically: ; Where, Represents the dielectric constant of GaN, Represents the critical breakdown electric field strength of GaN, q represents the electron charge, Represents the breakdown voltage of the PHEMT device, Represents the change in doping concentration between adjacent steps, Represents rounding up, represents the maximum solubility of carbon in GaN, and "max" represents taking the maximum value.

[0013] Optionally, the cap layer is specifically a GaN cap layer.

[0014] Optionally, the thickness range of the GaN cap layer is from 3 nm to 20 nm.

[0015] Optionally, the doping method of the C-doped GaN high-resistance layer is an acceptor doping method.

[0016] The beneficial effects brought by the technical solutions provided in the embodiments of the present invention at least include: In the embodiments of the present invention, by adopting a C-doped GaN high-resistance layer in a PHEMT device based on a gallium nitride (GaN) high-resistance layer and making the doping concentration change in an inverted step manner in the direction from the GaN buffer layer to the GaN channel layer, the problem of inaccurate doping concentration setting that overly relies on subjective experience is solved. Different from the traditional uniform doping method, the inverted step change doping method can be precisely adjusted according to the electric field distribution and carrier requirements, optimizing the resistance matching and electric field distribution. By combining the resistance matching principle and the principle of uniform electric field distribution, this design ensures that the electrical properties of the GaN high-resistance layer are reasonably distributed in different regions, avoiding leakage current and device defects caused by uneven doping concentration, and improving the stability and reliability of the device. By precisely controlling the doping concentration, the device can still maintain good performance under extreme conditions such as high frequency and high power, and avoids the deficiencies of previous doping designs that rely on experience. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer provided by an embodiment of the present invention. Detailed Embodiments

[0019] The following will describe the technical solutions in the present invention with reference to the drawings.

[0020] Refer to the attached drawings of the specification Figure 1 , which shows a schematic structural diagram of an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer provided by an embodiment of the present invention.

[0021] Figure 1In it, the hierarchical structure of the gallium nitride on silicon material epitaxial structure is shown, including multiple key layers. From bottom to top, the structure in the figure includes: a silicon substrate, an AlN nucleation layer, a stepped AlGaN sub-buffer layer, a semi-insulating GaN sub-buffer layer, a GaN functional layer, an AlGaN back barrier layer, a GaN device layer, and a GaN gain layer. The stepped AlGaN sub-buffer layer and the semi-insulating GaN sub-buffer layer effectively alleviate the lattice mismatch problem between silicon and gallium nitride, reduce the generation of stress and defects, thereby improving the quality and stability of the epitaxial layer. This structural design improves the reliability, breakdown voltage resistance, and performance of the device by optimizing the thermal stress and electrical breakdown characteristics. Therefore, this design provides better quality assurance and performance advantages for the commercial application of gallium nitride on silicon materials.

[0022] An embodiment of the present invention provides an epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer, including a substrate layer, a GaN buffer layer, a GaN high-resistance layer, a GaN channel layer, an InGaN barrier layer, and a cap layer; the substrate layer, the GaN buffer layer, the GaN high-resistance layer, the GaN channel layer, the InGaN barrier layer, and the cap layer are sequentially stacked; the GaN high-resistance layer is a C-doped GaN high-resistance layer, wherein the doping concentration of the C-doped GaN high-resistance layer changes in an inverted step manner in the direction from the GaN buffer layer to the GaN channel layer; the number of concentration steps of the C-doped GaN high-resistance layer conforms to the principle of resistance matching and the principle of uniform electric field distribution.

[0023] Among them, the substrate layer is the foundation of the device, providing support and physical stability. The role of the GaN buffer layer is to reduce the lattice mismatch between the substrate and the GaN high-resistance layer, reduce defects and stress, and improve the electrical performance of the device. It provides a good growth foundation for the upper GaN high-resistance layer and GaN channel layer. The GaN high-resistance layer is used to provide high-resistance characteristics, prevent current leakage, and provide an appropriate environment for the two-dimensional electron gas (2DEG) of the device. Doping with carbon (C) can reduce the carrier concentration to ensure that this layer has a high resistance. The GaN channel layer provides a conduction path and is the region where current flows from the source to the drain. By forming a two-dimensional electron gas (2DEG) through the heterojunction with the InGaN layer, the GaN channel layer realizes high-mobility electron transport. The InGaN barrier layer is used to enhance the formation of the two-dimensional electron gas. Through the bandgap difference with the GaN channel layer, the performance and efficiency of the device are improved. It helps to control the electron density of the device and optimize the electric field distribution. The cap layer is usually a layer of material located above the GaN channel layer, and it mainly plays the role of protection and optimizing the electric field distribution. The cap layer helps to form a good two-dimensional electron gas and improve the switching performance of the device.

[0024] Specifically, the principle of resistance matching means that in device design, it is required to reasonably match the resistance values of different layers to avoid excessive voltage drops or uneven current distributions during the transmission of current between different layers. This helps to improve the conductivity of the device, reduce thermal effects and current leakage, thereby enhancing the overall efficiency and stability of the device. The principle of uniform electric field distribution is to ensure that the electric field distribution between layers in the device is as uniform as possible, avoiding electron breakdown or excessive carrier acceleration caused by overly strong local electric fields, which would affect the stability and performance of the device. By controlling the distribution of doping concentration, the electric field can be made more uniform between different layers, thus ensuring the smooth flow of current inside the device. The inverted stepped doping concentration design of the C-doped GaN high-resistance layer can optimize these two principles: by precisely adjusting the doping concentration of each layer, uneven current flow and excessive acceleration are avoided, ensuring that the electrical properties of the GaN high-resistance layer are reasonably distributed, thereby improving the efficiency, stability, and reliability of the PHEMT device.

[0025] In the actual application process, through the design of the C-doped GaN high-resistance layer with an inverted stepped change, the doping concentration gradually changes in the direction from the GaN buffer layer to the GaN channel layer. This can avoid the deficiency of the traditional uniform doping method in precisely adjusting the electric field and carriers. The inverted stepped doping concentration can be optimized according to the electrical property requirements of different regions, effectively avoiding leakage current and current leakage caused by non-uniform doping, ensuring the uniform distribution of resistance and electric field, and improving the overall performance of the device.

[0026] In the embodiment of the present invention, by using a C-doped GaN high-resistance layer in a PHEMT device based on a gallium nitride (GaN) high-resistance layer and making the doping concentration change in an inverted stepped manner in the direction from the GaN buffer layer to the GaN channel layer, the problem of inaccurate doping concentration setting that overly relies on subjective experience is solved. Different from the traditional uniform doping method, the inverted stepped doping method can be precisely adjusted according to the electric field distribution and carrier requirements, optimizing the resistance matching and electric field distribution. By combining the principle of resistance matching and the principle of uniform electric field distribution, this design ensures that the electrical properties of the GaN high-resistance layer in different regions are reasonably distributed, avoiding leakage current and device defects caused by non-uniform doping concentration, and improving the stability and reliability of the device. By precisely controlling the doping concentration, the device can still maintain good performance under extreme conditions such as high frequency and high power, and avoid the deficiencies of previous doping designs that relied on experience.

[0027] In a possible implementation manner, the substrate layer includes a Si substrate and a sapphire substrate.

[0028] It should be noted that, as the substrate layer materials, Si substrates and sapphire substrates can provide cost - effectiveness and excellent thermal conductivity, support the growth of GaN layers and optimize device performance. Si substrates are relatively inexpensive and suitable for large - scale production, while sapphire substrates have better thermal management performance and are commonly used in high - power applications.

[0029] In a possible implementation, it further includes: a source electrode, a drain electrode and a gate electrode; The source electrode is in contact with the cap layer, and the source electrode and the drain electrode are respectively in contact with the InGaN barrier layer.

[0030] It should be noted that the source electrode is in contact with the cap layer to adjust the electric field by using the cap layer and optimize the formation of two - dimensional electron gas; at the same time, the source electrode and the drain electrode are respectively in contact with the InGaN barrier layer to enhance the control of the electron density of the device by using the band - gap characteristics of InGaN, improving the performance and stability of the device. This design ensures good current control and device reliability.

[0031] In a possible implementation, in combination with the constraint condition that the thermal resistance of the C - doped GaN high - resistance layer is less than a preset thermal resistance, the constraint condition for the thickness of the C - doped GaN high - resistance layer is determined. The constraint condition is specifically: ; Wherein, represents the thermal conductivity of GaN, represents the thermal resistance of the C - doped GaN high - resistance layer, represents the preset thermal resistance, represents the thickness of the C - doped GaN high - resistance layer, represents the breakdown voltage of the PHEMT device, represents the breakdown voltage threshold of the PHEMT device, represents the critical breakdown electric field strength of GaN.

[0032] Among them, the thermal conductivity of GaN is the ability of the GaN material to conduct heat. The higher the thermal conductivity, the more effectively the material can conduct heat. The thermal resistance of the C - doped GaN high - resistance layer refers to the thermal resistance of the carbon - doped GaN high - resistance layer, representing the resistance of the material to heat flow. The higher the thermal resistance, the worse the material's ability to conduct heat flow. The breakdown voltage of the PHEMT device is the maximum voltage value that the PHEMT device can withstand. Exceeding this voltage, the device may break down and fail. The critical breakdown electric field strength of GaN is the maximum electric field strength that the GaN material can withstand at breakdown, determining the voltage - withstand capacity of the device.

[0033] It should be noted that by combining the thermal resistance of the C-doped GaN high-resistance layer with the constraint condition of the preset thermal resistance in the design, the thickness of the GaN high-resistance layer is accurately determined to ensure that its thermal resistance is less than the preset value, thereby optimizing the thermal management performance of the device. At the same time, the scheme also takes into account the breakdown voltage of the PHEMT device and the critical breakdown electric field strength of the GaN material, avoiding device failure caused by overheating or excessive voltage. Through these precise designs, the device can maintain excellent stability and high performance under high-power and high-frequency conditions, avoiding performance degradation caused by poor thermal management or uneven electric field distribution in traditional designs.

[0034] Optionally, the preset thermal resistance can be set to 10 K / W.

[0035] In a possible implementation manner, based on the thickness of the C-doped GaN high-resistance layer that meets the constraint condition, when the tunneling current density of the heterojunction formed by the GaN channel layer and the InGaN barrier layer is less than the preset tunneling current density, the maximum doping concentration of the C-doped GaN high-resistance layer is determined by combining the carrier freeze model.

[0036] Among them, the carrier freeze model is a model used to describe that in semiconductor materials, carriers (such as electrons and holes) are "frozen" in specific states due to lack of sufficient energy at low temperatures or under certain high electric fields. It is mainly used to describe the phenomenon that the dynamic behavior of carriers is restricted or unable to move under high electric fields or low temperatures. Through this model, the behavior of carriers in materials can be better understood and predicted, especially the characteristics of current passing through obstacles in semiconductor materials. By combining the carrier freeze model, the doping concentration of the C-doped GaN high-resistance layer is optimized to ensure that under specific conditions, the doping concentration will not cause excessive carriers to be generated, thereby maintaining the high-resistance characteristics of the GaN high-resistance layer. By controlling the tunneling current density in the heterojunction of the GaN channel layer and the InGaN barrier layer, the influence of excessive tunneling current on the performance of the device is avoided. This scheme ensures that in high-power applications, the device can maintain stability, effectively control current leakage at the same time, optimize the doping concentration, and improve the working efficiency and reliability of the device under high-frequency and high-power conditions.

[0037] In a possible implementation manner, the calculation method of the maximum doping concentration is specifically as follows: ; Among them, represents the electron mobility of GaN at different C doping concentrations, represents the maximum doping concentration, q represents the electron charge quantity, represents the resistivity of GaN at different C doping concentrations, represents the tunneling current density, Represents the defect density of the C-doped GaN high-resistance layer, Represents the Trap-assisted tunneling current related to Represents the carrier diffusion current of the C-doped GaN high-resistance layer, Represents the effective Richardson constant reflecting the hot electron emission ability of C-doped GaN, Represents the barrier height of the InGaN barrier layer, e represents the natural constant, T represents the operating temperature of the PHEMT device, k represents the Boltzmann constant, Represents the preset tunneling current density, Represents the electron diffusion coefficient of GaN, Represents the dielectric constant of GaN, Represents the critical breakdown electric field strength of GaN, E t Represents the trap energy level depth of C-doped GaN, E represents the electric field strength borne by the C-doped GaN high-resistance layer in the PHEMT device, π represents the pi, Represents the Related electron diffusion coefficient.

[0038] Among them, the electron mobility of GaN measures the ability of electrons to respond to the electric field and migrate in the material. The electron mobility of GaN material affects its conductivity. The electron mobilities of GaN with different C doping concentrations are different, and a high mobility means a higher conductivity. The resistivity of GaN represents the resistance of the material itself to the flow of current. The resistivity of GaN material depends on its doping concentration, and the resistivity of the carbon-doped GaN high-resistance layer is usually high. The tunneling current density is the current density per unit area, representing the current generated by the tunneling effect of electrons through the barrier. An excessively high tunneling current will cause device leakage and affect its performance. The trap-assisted tunneling current is the tunneling current caused by material defects or trap sites. These traps may capture carriers and enhance the tunneling effect, affecting the device performance. The effective Richardson constant of the hot electron emission ability describes the electron density in the thermionic emission process, representing the thermal emission ability of electrons in the material, and affecting the device performance at high temperatures. The barrier height of the InGaN barrier layer describes the bandgap in electron transport of the InGaN layer, affecting the migration of electrons between the channel and the barrier. The trap energy level depth refers to the energy level position caused by defects or impurities in the material, and these energy levels affect the migration and tunneling behavior of electrons. The critical breakdown electric field strength of GaN is the maximum electric field strength that GaN material can withstand. When the electric field strength exceeds this value, the material will break down, resulting in device failure.

[0039] It should be noted that an appropriate C doping concentration can avoid the formation of excessive carriers, while increasing the resistance of the GaN layer. Especially in high-frequency and high-power applications, it can reduce leakage current and improve the stability of the device. By precisely calculating the doping concentration of the C-doped GaN high-resistance layer and considering multiple factors such as tunneling current density, carrier diffusion current, trap energy level depth, etc., it helps to optimize the electrical properties and thermal management of the GaN high-resistance layer. By controlling the tunneling current and electric field strength, it ensures that the device can still maintain good performance in high-frequency and high-power environments and avoids device failure caused by excessive tunneling current and electric field. In addition, this method avoids the deficiency of relying on experience through a scientific calculation method, provides a more accurate and reliable doping concentration design, and helps to improve the stability, reliability, and performance of the device.

[0040] In a possible implementation manner, the specific calculation formula for the number of concentration steps is as follows: ; Wherein, represents the GaN dielectric constant, represents the GaN critical breakdown electric field strength, q represents the electron charge, represents the breakdown voltage of the PHEMT device, represents the change in doping concentration between adjacent steps, represents rounding up, represents the maximum solubility of carbon in GaN, and max represents taking the maximum value.

[0041] Wherein, the change in doping concentration between adjacent steps represents the difference in doping concentration between two adjacent layers in the concentration step. The change in doping concentration affects the resistance characteristics of the GaN layer. The maximum solubility refers to the maximum doping concentration of carbon in the GaN material. By precisely calculating the number of concentration steps and combining multiple factors such as the dielectric constant of GaN, the critical breakdown electric field strength, and the breakdown voltage of the PHEMT device, it ensures a reasonable gradient of doping concentration, thereby optimizing the electric field distribution and resistance matching. By controlling the change in doping concentration and the maximum solubility, it effectively avoids defects or current leakage problems caused by excessive carbon doping, further improving the performance and stability of the device. This design enables the device to maintain better stability and efficiency in high-frequency and high-power applications, while increasing the tolerance to high-power and strong electric field working conditions.

[0042] Wherein, .

[0043] In a possible implementation manner, the cap layer is specifically a GaN cap layer.

[0044] It should be noted that the GaN cap layer refers to a layer of gallium nitride material located above the GaN channel layer. Its main function is to optimize the formation of two-dimensional electron gas, enhance the electric field control, thereby improving the switching performance of the PHEMT device. In addition, the GaN cap layer helps to improve the stability of the device, improve thermal management and reduce leakage current.

[0045] In a possible implementation, the thickness range of the GaN cap layer is from 3 nm to 20 nm.

[0046] It should be noted that the thickness range of the GaN cap layer is set from 3 nm to 20 nm. This range can effectively optimize the formation of two-dimensional electron gas while ensuring uniform electric field distribution. A suitable cap layer thickness helps to improve the switching performance and stability of the PHEMT device, while avoiding thermal management problems and device instability caused by too thick or too thin cap layers.

[0047] In a possible implementation, the doping method of the C-doped GaN high-resistance layer is an acceptor doping method.

[0048] Among them, acceptor doping is a doping method, which refers to adding acceptor elements to the material. These elements can accept electrons and generate holes. In GaN materials, carbon (C) doping is usually used as an acceptor dopant. Carbon atoms accept electrons in the GaN lattice to form holes, thereby reducing the carrier concentration and increasing the resistivity of the material. This doping method makes the GaN layer have a relatively high resistance, ensuring that the GaN high-resistance layer can effectively prevent current leakage and enhance the stability and reliability of the device.

[0049] In the actual application process, the epitaxial structure of the PHEMT device based on the gallium nitride high-resistance layer precisely designs each layer, including the substrate layer, GaN buffer layer, GaN high-resistance layer, GaN channel layer, InGaN barrier layer and cap layer, so that the device can maintain excellent stability and high performance in high-frequency and high-power applications. The C-doped GaN high-resistance layer adopts a reverse stepped doping concentration, avoiding the uneven electric field distribution caused by the traditional uniform doping method, optimizing the resistance matching and electric field distribution, and effectively preventing current leakage. In addition, combined with the thermal resistance and electric field optimization design, it ensures the tolerance of the device under strong electric field and high-power conditions, improving the performance and reliability. The overall solution improves the stability of the device, reduces leakage current, optimizes thermal management, and avoids possible defect problems in the traditional design.

[0050] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An epitaxial structure of a PHEMT device based on a gallium nitride high-resistance layer, characterized in that: It includes a substrate layer, a GaN buffer layer, a GaN high resistance layer, a GaN channel layer, an InGaN barrier layer and a cap layer; The substrate layer, the GaN buffer layer, the GaN high resistance layer, the GaN channel layer, the InGaN barrier layer and the cap layer are stacked in sequence; The GaN high resistance layer is a C-doped GaN high resistance layer, wherein the doping concentration of the C-doped GaN high resistance layer changes in an inverse step in the direction from the GaN buffer layer to the GaN channel layer; The number of concentration steps of the C-doped GaN high-resistance layer complies with the resistance matching principle and the electric field uniform distribution principle.

2. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 1, characterized in that: The substrate layer includes a Si substrate and a sapphire substrate.

3. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 1, characterized in that: Also includes: Source, drain and gate; The source electrode is arranged in contact with the cap layer, and the source electrode and the drain electrode are arranged in contact with the InGaN barrier layer respectively.

4. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 1, characterized in that: Combined with the constraint condition that the thermal resistance of the C-doped GaN high-resistance layer is less than the preset thermal resistance, the constraint condition of the thickness of the C-doped GaN high-resistance layer is determined, and the constraint condition is specifically: ； in, represents the thermal conductivity of GaN, represents the thermal resistance of the C-doped GaN high-resistance layer, Indicates the preset thermal resistance, represents the thickness of the C-doped GaN high-resistance layer, Indicates the breakdown voltage of the PHEMT device, Indicates the breakdown voltage threshold of the PHEMT device, Represents the critical breakdown electric field strength of GaN.

5. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 4, characterized in that: Based on the thickness of the C-doped GaN high resistance layer that meets the constraint conditions, when the tunneling current density of the heterojunction formed by the GaN channel layer and the InGaN barrier layer is less than a preset tunneling current density, the maximum doping concentration of the C-doped GaN high resistance layer is determined in combination with a carrier freezing model.

6. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 5, characterized in that: The maximum doping concentration is calculated as follows: ； in, represents the GaN electron mobility at different C doping concentrations, represents the maximum doping concentration, q represents the electron charge, represents the resistivity of GaN at different C doping concentrations, is the tunneling current density, represents the defect density of C-doped GaN high resistance layer, Representation and The associated trap-assisted tunneling current, represents the carrier diffusion current of the C-doped GaN high resistance layer, represents the effective Richardson constant reflecting the thermal electron emission capability of C-doped GaN, represents the barrier height of the InGaN barrier layer, e represents the natural constant, T represents the operating temperature of the PHEMT device, k represents the Boltzmann constant, represents the preset tunneling current density, represents the GaN electron diffusion coefficient, represents the GaN dielectric constant, Indicates the critical breakdown electric field strength of GaN, E t represents the trap level depth of C-doped GaN, E represents the electric field strength borne by the C-doped GaN high-resistance layer in the PHEMT device, and π represents the circumference of a circle. Representation and The related electron diffusion coefficient.

7. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 6, characterized in that: The calculation formula for the number of concentration steps is specifically: ； in, represents the GaN dielectric constant, represents the critical breakdown electric field strength of GaN, q represents the electron charge, Indicates the breakdown voltage of the PHEMT device, represents the change in doping concentration between adjacent steps, Indicates rounding up. It represents the maximum solubility of carbon in GaN, and max represents the maximum value.

8. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 1, characterized in that: The cap layer is specifically a GaN cap layer.

9. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 8, characterized in that: The thickness of the GaN cap layer ranges from 3 nm to 20 nm.

10. The epitaxial structure of the PHEMT device based on the gallium nitride high resistance layer according to claim 9, characterized in that: The doping method of the C-doped GaN high resistance layer is acceptor doping method.

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