Diamond-based gallium nitride device of ohmic Schottky electrode and preparation method of diamond-based gallium nitride device
By setting a small ohmic contact area below the source electrode and introducing a Schottky contact, the problems of large subthreshold current and difficulty in adjusting linearity of gallium nitride HEMT devices are solved, thereby improving device performance.
Patent Information
- Application Number
- CN202511512641.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2026-01-13
AI Technical Summary
Existing gallium nitride HEMT devices suffer from large subthreshold currents and difficulty in adjusting linearity. Traditional ohmic contact electrodes have a large coverage area, resulting in large gate leakage currents, making it difficult to flexibly adjust the device linearity through gate-source capacitance design.
At least one first ohmic contact region with an area smaller than that of the source electrode is provided below the source electrode. It is distributed along the direction perpendicular to the source-drain connection to form multiple current paths. A potential barrier is introduced through a Schottky contact to change the electric field distribution and current path, thereby adjusting the linearity of the device.
The subthreshold current was reduced, enabling flexible adjustment of the device linearity, improving the device's subthreshold characteristics and electric field distribution, and enhancing the device's performance.
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Figure CN121335142A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gallium nitride HEMT device technology, and more particularly to a diamond-based gallium nitride device with an ohm-Schottky electrode and its fabrication method. Background Technology
[0002] Gallium nitride HEMT (High Electron Mobility Transistor) is a field-effect transistor based on gallium nitride wide bandgap semiconductor material. Its core advantages are high frequency, high voltage, high power, and high efficiency. It is the preferred device for high-frequency and high-power microwave electronic systems and is widely used in 5G communication, new energy vehicles, aerospace, radio frequency radar and other fields.
[0003] Traditional gallium nitride (GaN) HEMT devices use ohmic contacts for both the source and drain electrodes. These are single, integrated electrodes with a large coverage area. While using large ohmic contacts eliminates potential barriers and reduces contact resistance, the absence of a barrier between the ohmic electrode and the device channel leads to gate leakage current from the source, resulting in a large subthreshold current. Furthermore, the device's linearity is closely related to the gate-source capacitance. Since the traditional source / drain ohmic contacts are a single unit, the electric field in the active region is relatively uniform, and channel electrons flow approximately uniformly from the source to the drain electrode, making it difficult to adjust the device's linearity through flexible gate-source capacitance design. Summary of the Invention
[0004] This invention provides a diamond-based gallium nitride device with an ohm-Schottky electrode and its fabrication method, in order to solve the problems of large subthreshold current and difficulty in adjusting linearity in existing gallium nitride HEMT devices.
[0005] In a first aspect, embodiments of the present invention provide a diamond-based gallium nitride device with an ohm-Schottky electrode, comprising: a substrate, a channel layer, a source electrode, a drain electrode, and a gate electrode; the substrate is a diamond substrate; the source electrode and the drain electrode are disposed on the channel layer, and the gate electrode is disposed between the source electrode and the drain electrode; at least one first ohmic contact region with an area smaller than that of the source electrode is provided below the source electrode; the source electrode forms an ohmic contact with an epitaxial layer within the first ohmic contact region and a Schottky contact with an epitaxial layer outside the first ohmic contact region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line; the drain electrode forms an ohmic contact with the epitaxial layer below it.
[0006] In one possible implementation, the number of the first ohmic contact regions is at least two.
[0007] In one possible implementation, each of the first ohmic contact areas is non-uniformly distributed along a first direction.
[0008] In one possible implementation, the area of each of the first ohmic contact regions is the same.
[0009] In one possible implementation, a second ohmic contact area is provided below the drain electrode; the area of the second ohmic contact area is greater than or equal to the area of the drain electrode.
[0010] In one possible implementation, the substrate is a diamond substrate.
[0011] In one possible implementation, a barrier layer is further disposed above the channel layer; the source electrode forms an ohmic contact with the barrier layer within the first ohmic contact region and a portion of the channel layer; the source electrode forms a Schottky contact with the barrier layer outside the first ohmic contact region; and the drain electrode forms an ohmic contact with the barrier layer below it and a portion of the channel layer.
[0012] In one possible implementation, a nucleation layer, a buffer layer, and an insertion layer are provided sequentially from bottom to top between the substrate and the channel layer.
[0013] Secondly, embodiments of the present invention provide a method for fabricating a diamond-based gallium nitride device with an ohm-Schottky electrode, comprising: epitaxially growing a channel layer on a substrate; fabricating an ohmic contact region; wherein, at least one first ohmic contact region with an area smaller than that of the source electrode is fabricated in the source region; an ohmic contact region is fabricated in the drain region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line; fabricating a source electrode and a drain electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the drain electrode forms an ohmic contact with the epitaxial layer below it; and fabricating a gate electrode between the source electrode and the drain electrode to obtain a gallium nitride HEMT device.
[0014] In one possible implementation, the preparation of the ohmic contact region includes: preparing an N-type heavily doped region as the ohmic contact region by ion implantation or secondary epitaxial growth.
[0015] This invention provides a diamond-based gallium nitride device with an ohmic Schottky electrode and its fabrication method. At least one first ohmic contact region with an area smaller than the source electrode is provided below the source electrode. Each first ohmic contact region is distributed along a direction perpendicular to the source-drain connection. Each first ohmic contact region and the drain ohmic contact region form multiple current paths. On one hand, the Schottky source electrode with ohmic contact regions introduces a Schottky barrier by adding a Schottky electrode portion, reducing gate leakage current and thus improving the subthreshold characteristics of the device. On the other hand, by changing the distribution of the source ohmic contact region, the electric field distribution inside the device can be adjusted, changing the gate-source capacitance and the channel current path. Channel electrons flow from the ohmic contact region of the source electrode to the ohmic contact drain electrode, and the channel current is non-uniformly distributed in the active region of the device, achieving flexible adjustment of the device linearity. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the cross-sectional structure of a traditional gallium nitride HEMT device; Figure 2 This is a schematic diagram of the planar structure of a traditional gallium nitride HEMT device; Figure 3 This is a schematic cross-sectional view of the diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the planar structure of the diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the distribution of the first ohmic contact area provided in an embodiment of the present invention; Figure 6 This is another schematic diagram showing the distribution of the first ohmic contact area provided in an embodiment of the present invention; Figure 7 This is a schematic cross-sectional view of the epitaxial layer provided in an embodiment of the present invention; Figure 8 This is a schematic cross-sectional view of the grounding metal layer provided in an embodiment of the present invention; Figure 9 This is a schematic cross-sectional view of another diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention. Figure 10 This is a flowchart illustrating the preparation method provided in this embodiment of the invention. Detailed Implementation
[0017] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.
[0018] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.
[0019] The implementation of the present invention will be described in detail below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the cross-sectional structure of a traditional gallium nitride HEMT device. Figure 2 This is a schematic diagram of a traditional gallium nitride HEMT device planar structure. (Refer to...) Figure 1 and Figure 2 Gallium nitride (GaN) HEMT devices comprise a substrate, a GaN channel layer, an AlGaN barrier layer, a dielectric layer, a passivation layer, a Schottky gate electrode, an ohmic contact source electrode, and an ohmic contact drain electrode. In traditional GaN HEMT device structures, both the source and drain electrodes are under ohmic contacts, and the coverage area of these ohmic contacts should be as large as possible, typically the same as the area of the source and drain electrodes. Thus, the source electrode covers the source region to form a monolithic electrode, and the drain electrode covers the drain region to form a monolithic electrode. On the one hand, using ohmic contact electrodes with a large coverage area can minimize contact resistance. On the other hand, the source and drain electrodes completely cover the source and drain regions, ensuring a uniform distribution of channel current from the source electrode to the drain electrode within the active region.
[0020] Existing gallium nitride HEMT devices have ohmic contacts that uniformly cover the source region, which leads to problems such as large subthreshold current and difficulty in adjusting linearity.
[0021] This invention adjusts linearity and reduces subthreshold current by setting a small first ohmic contact region in the source electrode region, thereby adjusting the current path between the source and drain and changing the current distribution. The linearity of the device is closely related to the gate-source capacitance. By changing the distribution of the ohmic contact region, the internal electric field of the device is adjusted, thereby changing the gate-source capacitance and channel current, and thus adjusting the device linearity.
[0022] Figure 3 This is a schematic cross-sectional view of the diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention. Figure 4This is a schematic diagram of the planar structure of a diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention. (Refer to...) Figure 3 , Figure 4 The device includes: a substrate, a channel layer, a source electrode, a drain electrode, and a gate electrode; the substrate is a diamond substrate; the source electrode and the drain electrode are disposed on the channel layer, and the gate electrode is disposed between the source electrode and the drain electrode; at least one first ohmic contact region with an area smaller than that of the source electrode is provided below the source electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line; the drain electrode forms an ohmic contact with the epitaxial layer below it.
[0023] In some embodiments, the substrate is a diamond substrate.
[0024] It should be noted that as device power density increases, heat dissipation becomes increasingly problematic, limiting the device's application range. Diamond substrates possess excellent thermal conductivity, effectively addressing near-junction heat dissipation issues and enabling devices to operate at higher power densities with lower junction temperatures and higher reliability.
[0025] In some embodiments, the source electrode and the drain electrode are disposed on the channel layer, and the source electrode and the drain electrode are respectively disposed at both ends of the channel layer, and the gate electrode is disposed between the source electrode and the drain electrode; For example, the source electrode is located at one end of the channel layer, and the drain electrode is located at the other end of the channel layer. The region between the source and drain is the active region. The gate electrode is located between the source and drain electrodes and controls the channel to turn on or off and adjusts the channel current.
[0026] In some embodiments, at least one first ohmic contact region with an area smaller than that of the source electrode is disposed below the source electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the Schottky contact region surrounds each of the first ohmic contact regions; the first ohmic contact regions are distributed along a first direction; the first direction is perpendicular to the source-drain connection line.
[0027] In this embodiment, the Schottky contact region surrounds each of the ohmic contact regions, forming a potential barrier around the ohmic contact regions, thereby also forming a potential barrier between the source and the gate.
[0028] It should be noted that the area of the first ohmic contact region is smaller than the area of the source electrode. Here, the area refers to the area projected vertically. Unlike existing methods where "the ohmic contact and source electrode areas are the same," the ohmic contact region in this embodiment is smaller and is divided into one or more isolated regions. Because the ohmic contact region is smaller, the area below the source electrode is divided into an area inside and an area outside the first ohmic contact region. A metal is used to cover the source electrode region to form the source electrode. The source electrode forms an ohmic contact with the epitaxial layer inside the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region. It is important to note that the source electrode is formed as a single unit, but the contact methods in different areas beneath it differ.
[0029] It should be further explained that, regarding the distribution of the first ohmic contact regions, the Schottky contact regions surround each of the aforementioned ohmic contact regions; each first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection. Each first ohmic contact region, distributed along the first direction, can face the drain electrode without obstruction. Each first ohmic contact region can form an independent current path towards the drain electrode. Therefore, by changing the distribution of the first ohmic contact regions, the current path and current distribution of the active region can be changed.
[0030] For example, the number of the first ohmic contact areas is at least two. For instance, the number of the first ohmic contact areas can be two, three, or four, etc.
[0031] For example, each of the first ohmic contact areas is non-uniformly distributed along the first direction. Figure 5 This is a schematic diagram of the distribution of the first ohmic contact area provided in an embodiment of the present invention; Figure 6 This is another schematic diagram showing the distribution of the first ohmic contact region provided in an embodiment of the present invention; see reference. Figure 5 , Figure 6 For example, the two first ohmic contact regions can be concentrated in the central region of the source electrode or in either side of the source electrode.
[0032] For example, each of the first ohmic contact regions is uniformly distributed along a first direction. Compared to the ohmic contact method that completely covers the source electrode, the uniformly distributed first ohmic contact regions with smaller areas can also form non-uniformly distributed current paths.
[0033] For example, each of the first ohmic contact areas has the same area size.
[0034] For example, the vertical projection shape of the first ohmic contact area is a square, rectangle, or circle.
[0035] In some embodiments, a second ohmic contact region is provided below the drain electrode, and the drain electrode forms an ohmic contact with the epitaxial layer of the second ohmic contact region below it.
[0036] For example, the area of the drain electrode is less than or equal to the area of the second ohmic contact region.
[0037] This invention provides an embodiment of the invention by providing at least one first ohmic contact region with an area smaller than that of the source electrode below the source electrode; each first ohmic contact region is distributed along a direction perpendicular to the source-drain connection; each first ohmic contact region and the drain ohmic contact region form multiple current paths; on the one hand, the Schottky source electrode with ohmic contact regions introduces a Schottky barrier by adding a Schottky electrode portion, reducing gate leakage current and thus improving the subthreshold characteristics of the device; on the other hand, by changing the distribution of the source ohmic contact region, the electric field distribution inside the device can be adjusted, changing the gate-source capacitance and the channel current path, and the channel electrons flow from the ohmic contact region of the source to the ohmic contact drain electrode, and the channel current is non-uniformly distributed in the active region of the device, thereby achieving flexible adjustment of the device linearity.
[0038] It should be noted that although the embodiments of the present invention have a smaller ohmic contact area and divide the ohmic contact area into multiple independent regions, the area of the source electrode is not reduced because the entire source electrode covers all the ohmic contact areas. The electrode area can be guaranteed to be large enough to facilitate soldering or wire bonding with external circuits.
[0039] In one possible implementation, a barrier layer is further disposed above the channel layer; the source electrode forms an ohmic contact with the barrier layer within the first ohmic contact region and a portion of the channel layer; the source electrode forms a Schottky contact with the barrier layer outside the first ohmic contact region; and the drain electrode forms an ohmic contact with the barrier layer below it and a portion of the channel layer.
[0040] It should be noted that ion implantation can be used to form the ohmic contact region. For example, the ion implantation depth is relatively deep, at least penetrating the barrier layer and passing through the interface between the barrier layer and the channel layer, that is, the portion penetrating into the channel layer.
[0041] For example, the barrier layer is an aluminum gallium nitride barrier layer.
[0042] It should be noted that the channel layer and the barrier layer constitute the epitaxial layer of the gallium nitride heterojunction. A two-dimensional electron gas channel is formed at the interface between the channel layer and the barrier layer.
[0043] For example, the channel layer is an intrinsically GaN layer that is not intentionally doped. The thickness of the channel layer is between 100 nm and 300 nm.
[0044] For example, the material of the barrier layer includes one of AlGaN, AlInN, AlInGaN, AlN, AlScN, etc. The thickness of the barrier layer is between 5nm and 50nm.
[0045] Figure 7 This is a schematic cross-sectional view of the epitaxial layer provided in an embodiment of the present invention; see reference. Figure 7 In one possible implementation, a nucleation layer, a buffer layer, and an insertion layer are provided sequentially from bottom to top between the substrate and the channel layer.
[0046] For example, the gallium nitride heterojunction epitaxial layer further includes a nucleation layer, a buffer layer, an insertion layer, and a cap layer. The nucleation layer is located above the substrate, the buffer layer is located above the nucleation layer, the insertion layer is located between the channel layer and the barrier layer, and the cap layer is located above the barrier layer.
[0047] In one possible implementation, an interface layer is provided between the diamond substrate and the gallium nitride epitaxial layer.
[0048] Figure 8 This is a cross-sectional structural diagram of the grounding metal layer provided in an embodiment of the present invention; see reference. Figure 8 In one possible implementation, a ground metal layer is disposed on the back side of the substrate. The source electrode is connected to the ground metal layer through a through-hole penetrating the substrate.
[0049] In one possible implementation, the gate electrode is a T-type or Γ-type gate electrode structure. The gate electrode includes a gate root and a gate cap.
[0050] In one possible implementation, a dielectric layer / passivation layer is also provided on the device surface.
[0051] For example, the dielectric layer is made of one or more materials selected from silicon nitride, silicon dioxide, aluminum oxide, hafnium oxide, etc. For example, the passivation layer is made of one or more materials selected from silicon nitride, silicon dioxide, aluminum oxide, hafnium oxide, etc.
[0052] In one possible implementation, the device structure, from bottom to top, includes a diamond substrate, a gallium nitride heterojunction epitaxial layer, a gate electrode, a source electrode, and a drain electrode. A two-dimensional electron gas channel is formed in the gallium nitride heterojunction epitaxial layer. The gate electrode, source electrode, and drain electrode are all located on the upper surface of the gallium nitride heterojunction epitaxial material. The gate electrode is a Schottky contact electrode, the source electrode is a Schottky contact electrode with an ohmic contact region, and the drain electrode is an ohmic contact electrode. The source electrode and drain electrode are located at opposite ends of the device channel, and the gate electrode is located between the source electrode and the drain electrode. Below the source electrode is an ohmic contact region, forming an ohmic contact with the source electrode and the ohmic contact region below it. Other portions of the source electrode form Schottky contacts with the gallium nitride heterojunction epitaxial layer. The ohmic contact region below the source electrode consists of one or more discrete ohmic contact regions. The area of the source electrode is larger than the total area of the ohmic contact region below it. Below the drain electrode is an ohmic contact region, forming an ohmic contact with the drain electrode and the ohmic contact region below it. The ohmic contact region below the drain electrode is a single, independent ohmic contact region. The area of the drain electrode is less than or equal to the area of the ohmic contact region below it.
[0053] In one possible implementation, the device is a single-gate or multi-gate finger structure. Figure 9 This is a schematic cross-sectional view of another diamond-based gallium nitride device with an ohm-Schottky electrode provided in an embodiment of the present invention; see reference. Figure 9 This illustrates a multi-gate finger structure.
[0054] Figure 10 This is a flowchart illustrating the preparation method provided in this embodiment of the invention. (Refer to...) Figure 10 This invention provides a method for fabricating a diamond-based gallium nitride device with an ohm-Schottky electrode, comprising: Step 101: Epitaxially grow a trench layer on the substrate.
[0055] For example, after growing the channel layer, the method further includes growing a barrier layer on the channel layer.
[0056] Step 102: Prepare an ohmic contact region; wherein, at least one first ohmic contact region with an area smaller than that of the source electrode is prepared in the source region; an ohmic contact region is prepared in the drain region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line.
[0057] In one possible implementation, the preparation of the ohmic contact region includes: preparing an N-type heavily doped region as the ohmic contact region by ion implantation or secondary epitaxial growth.
[0058] For example, the ohmic contact region below the source and drain electrodes is an N-type heavily doped region grown by ion implantation or secondary epitaxy, in contact with a two-dimensional electron gas, with a doping concentration of 10. 18 cm -2 and 1020 cm -3 between.
[0059] Step 103: Prepare source electrode and drain electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the drain electrode forms an ohmic contact with the epitaxial layer below it.
[0060] Step 104: Fabricate a gate electrode between the source electrode and the drain electrode to obtain a gallium nitride HEMT device.
[0061] The gallium nitride HEMT device fabricated in this embodiment of the invention has at least one first ohmic contact region with an area smaller than that of the source electrode below the source electrode; each first ohmic contact region is distributed along a direction perpendicular to the source-drain connection; each first ohmic contact region and the drain ohmic contact region form multiple current paths; on the one hand, the Schottky source electrode with ohmic contact regions introduces a Schottky barrier by adding a Schottky electrode portion, reducing gate leakage current and thus improving the subthreshold characteristics of the device; on the other hand, by changing the distribution of the source ohmic contact region, the electric field distribution inside the device can be adjusted, changing the gate-source capacitance and the channel current path, and the channel electrons flow from the ohmic contact region of the source electrode to the ohmic contact drain electrode, and the channel current is non-uniformly distributed in the active region of the device, realizing flexible adjustment of the device linearity.
[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A diamond-based gallium nitride device with an ohm-Schottky electrode, characterized in that, include: Substrate, channel layer, source electrode, drain electrode, and gate electrode; The substrate is a diamond substrate; The source electrode and drain electrode are disposed on the channel layer, and the gate electrode is disposed between the source electrode and the drain electrode; Below the source electrode, there is at least one first ohmic contact region with an area smaller than that of the source electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line; The drain electrode forms an ohmic contact with the underlying epitaxial layer.
2. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 1, characterized in that, The number of the first ohmic contact areas is at least two.
3. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 2, characterized in that, Each of the first ohmic contact areas is non-uniformly distributed along the first direction.
4. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 2, characterized in that, The area of each of the first ohmic contact regions is the same.
5. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 1, characterized in that, A second ohmic contact area is provided below the drain electrode; The area of the second ohmic contact region is greater than or equal to the area of the drain electrode.
6. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 1, characterized in that, The area of the Schottky contact surrounds each of the first ohmic contact areas.
7. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 1, characterized in that, A barrier layer is also disposed above the channel layer; The source electrode forms an ohmic contact with the barrier layer and part of the channel layer in the first ohmic contact region. The source electrode forms a Schottky contact with the barrier layer outside the first ohmic contact region; The drain electrode forms an ohmic contact with the barrier layer below it and part of the channel layer.
8. The diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 1, characterized in that, Between the substrate and the channel layer, a nucleation layer, a buffer layer, and an insertion layer are provided sequentially from bottom to top.
9. A method for fabricating a diamond-based gallium nitride device with an ohm-Schottky electrode, characterized in that, include: Epitaxial growth of a channel layer on a substrate; An ohmic contact region is prepared; wherein at least one first ohmic contact region with an area smaller than that of the source electrode is prepared in the source region. An ohmic contact region is fabricated in the drain region; the first ohmic contact region is distributed along a first direction; the first direction is perpendicular to the source-drain connection line; Fabricate a source electrode and a drain electrode; the source electrode forms an ohmic contact with the epitaxial layer within the first ohmic contact region and a Schottky contact with the epitaxial layer outside the first ohmic contact region; the drain electrode forms an ohmic contact with the epitaxial layer below it; A gate electrode is fabricated between the source electrode and the drain electrode to obtain a gallium nitride HEMT device.
10. The method for fabricating a diamond-based gallium nitride device with an ohm-Schottky electrode as described in claim 9, characterized in that, The preparation of the ohmic contact region includes: N-type heavily doped regions were prepared by ion implantation or secondary epitaxial growth to serve as ohmic contact regions.