Diamond composite conductive inversion channel enhanced field effect transistor and preparation method thereof

Abstract

The invention discloses a diamond composite conductive inversion channel enhanced field effect transistor and a preparation method thereof. The field effect transistor adopts an n-type diamond epitaxial layer and a hydrogen terminal p-type conductive layer with p-type two-dimensional hole gas to form an under-gate channel. When positive gate voltage is applied to the gate electrode in the enhanced field effect transistor provided by the invention, the two-dimensional hole gas of the under-gate channel is conductive, the hole is repelled and exhausted, and the channel is turned off; when the gate electrode is in zero gate voltage, electrons of the n-type diamond epitaxial layer and holes of the hydrogen terminal p-type conductive layer are counteracted and neutralized under the condition that the concentration is equivalent, and a channel is turned off; when negative gate voltage is applied to the gate electrode, holes of the hydrogen terminal p-type conductive layer are attracted, electrons of the n-type diamond epitaxial layer are repelled, an inversion channel is formed, the channel is conducted, and therefore the conducted channel with good conductivity is achieved. Source and drain current formed on the hydrogen terminal p-type conductive layer can improve the under-gate carrier concentration of the field effect transistor, improve the current density, reduce the channel resistance and enhance the gate control capability.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a diamond composite conductivity inversion channel enhancement type field effect transistor and a preparation method thereof. Background Art

[0002] Compared with other semiconductor materials, diamond, as the "ultimate semiconductor", has obvious characteristic advantages, such as large bandgap, strong breakdown field, high carrier mobility, high thermal conductivity, etc. Therefore, it has great potential in high-frequency, high-power, high-temperature electronic devices, nuclear radiation detectors, optoelectronic devices, micro-electromechanical systems (MEMS) and other application fields. At present, in the preparation of diamond field-effect transistors, the surface hydrogen terminal treatment method is usually used to form a p-type two-dimensional hole gas conductive layer on the diamond surface under the action of transfer doping, and then the device preparation is completed through subsequent device processes. However, this device is naturally depleted, and its control difficulty and power consumption problems limit its application in fields such as logic circuit design and power consumption management.

[0003] A p-type two-dimensional hole gas conductive layer will be formed on the surface of hydrogen-terminated diamond. If an enhancement field-effect transistor is to be realized, additional processes are needed to deplete the holes with high surface density on the surface of the hydrogen-terminated diamond. For example, local conductivity regulation can be achieved by bombarding the surface of the hydrogen-terminated diamond with argon ion beams, or charge regulation can be achieved by using gate dielectrics such as aluminum nitride and boron nitride. However, these processes will reduce the carrier concentration of the device channel, increase the channel on-resistance, and reduce the source-drain output current. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a diamond composite conductivity inversion channel enhanced field effect transistor and a preparation method thereof. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a diamond composite conductivity inversion channel enhanced field effect transistor, comprising:

[0006] Intrinsic diamond layer, n-type diamond epitaxial layer, hydrogen-terminated p-type conductive layer, source electrode, drain electrode, gate dielectric and gate electrode; wherein,

[0007] The n-type diamond epitaxial layer is arranged in a gate position region in the middle of the upper surface of the intrinsic diamond layer;

[0008] The hydrogen-terminated p-type conductive layer is disposed in a region below the upper surface of the intrinsic diamond layer;

[0009] The source electrode is disposed at one end of the upper surface of the intrinsic diamond layer;

[0010] The drain electrode is disposed at the other end of the upper surface of the intrinsic diamond layer;

[0011] The gate dielectric is disposed on the remaining area of ​​the upper surface of the intrinsic diamond layer and the upper surface of the n-type diamond epitaxial layer;

[0012] The gate electrode is arranged on the upper surface of the gate dielectric corresponding to the gate position area.

[0013] In one embodiment of the present invention, the n-type diamond epitaxial layer comprises:

[0014] Phosphorus, lithium, sodium doped diamond layer or selenium-phosphorus co-doped diamond layer.

[0015] In one embodiment of the present invention, the n-type diamond epitaxial layer and the hydrogen-terminated p-type conductive layer form a channel under the gate.

[0016] In one embodiment of the present invention, the carrier surface density of the hydrogen-terminated p-type conductive layer is 1×10 12 cm -2 -10 14 cm -2 , the carrier mobility is 50cm 2 / (V·S)-200cm 2 / (V·S).

[0017] In one embodiment of the present invention, the gate dielectric material includes Al 2 O 3 , thickness is 10nm-25nm.

[0018] In a second aspect, the present invention provides a method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor, comprising:

[0019] obtaining an intrinsic diamond layer as a substrate;

[0020] Growing an n-type diamond epitaxial layer in a gate location region in the middle of the upper surface of the intrinsic diamond layer;

[0021] Performing hydrogen termination treatment on the upper surface of the intrinsic diamond layer to generate a hydrogen-terminated p-type conductive layer in a region below the upper surface of the intrinsic diamond layer;

[0022] Depositing a source electrode and a drain electrode at two ends of the upper surface of the intrinsic diamond layer respectively;

[0023] Preparing a gate dielectric on the remaining area of ​​the upper surface of the intrinsic diamond layer and the upper surface of the n-type diamond epitaxial layer;

[0024] A gate electrode is prepared on the upper surface of the gate dielectric corresponding to the gate position area.

[0025] In one embodiment of the present invention, growing an n-type diamond epitaxial layer in a gate position region in the middle of the upper surface of the intrinsic diamond layer comprises:

[0026] Depositing a protective layer on the upper surface of the intrinsic diamond layer;

[0027] Removing the protective layer on the gate location area in the middle of the upper surface of the intrinsic diamond layer;

[0028] Under preset chamber conditions, growing an n-type diamond epitaxial layer on the upper surface of the intrinsic diamond layer;

[0029] The remaining protective layer on the upper surface of the intrinsic diamond layer is removed.

[0030] In one embodiment of the present invention, a protective layer is deposited on the upper surface of the intrinsic diamond layer, comprising:

[0031] A protective layer is deposited on the upper surface of the intrinsic diamond layer by electron beam evaporation or magnetron sputtering; wherein the material of the protective layer includes a titanium / gold alloy layer or a SiO 2 , thickness is 80-120nm.

[0032] In one embodiment of the present invention, hydrogen termination treatment is performed on the upper surface of the intrinsic diamond layer to generate a hydrogen-terminated p-type conductive layer in a region below the upper surface of the intrinsic diamond layer, comprising:

[0033] In the MPCVD equipment, a hydrogen-terminated p-type conductive layer is generated in the area below the upper surface of the intrinsic diamond layer by preset chamber conditions; wherein the preset chamber conditions include: hydrogen flow rate: 200sccm-400sccm, chamber pressure: 140mbar-160mbar, microwave power: 2kW-2.5kW, temperature: 650℃-850℃, methane flow rate: 5sccm-20sccm, and processing time: 10min-45min.

[0034] In one embodiment of the present invention, a gate dielectric is prepared on the remaining area of ​​the upper surface of the intrinsic diamond layer and the upper surface of the n-type diamond epitaxial layer, comprising:

[0035] Using an atomic layer deposition method, under preset process conditions, a gate dielectric is prepared in the remaining area of ​​the upper surface of the intrinsic diamond layer and the upper surface of the n-type diamond epitaxial layer; wherein the preset process conditions are a process temperature of 150°C-400°C and a thickness of the gate dielectric of 10nm-25nm.

[0036] Beneficial effects of the present invention:

[0037] In the scheme provided by the present invention, the field effect tube uses an n-type diamond epitaxial layer and a hydrogen-terminated p-type conductive layer with p-type two-dimensional hole gas to form a channel under the gate. When a positive gate voltage is applied to the gate electrode in the enhanced field effect tube proposed by the present invention, the two-dimensional hole gas in the channel under the gate conducts electricity, the holes are repelled and exhausted, and the channel is turned off; when the gate electrode is at zero gate voltage, the electrons in the n-type diamond epitaxial layer and the holes in the hydrogen-terminated p-type conductive layer are offset and neutralized when the concentrations are equivalent, and the channel is turned off; when a negative gate voltage is applied to the gate electrode, the holes in the hydrogen-terminated p-type conductive layer are attracted, and the electrons in the n-type diamond epitaxial layer are repelled, forming an inversion channel, and the channel is turned on, thereby realizing a conductive channel with better conductivity. The source-drain current formed in the hydrogen-terminated p-type conductive layer can increase the carrier concentration under the gate of the field effect tube, increase the current density, reduce the channel resistance, and enhance the gate control capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic structural diagram of a diamond composite conductivity inversion channel enhancement field effect transistor provided by an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the steps of a method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor provided by an embodiment of the present invention;

[0040] Figure 3 A schematic diagram of a process for preparing an n-type diamond epitaxial layer in a method for preparing a diamond composite conductivity inversion channel enhanced field effect transistor provided by an embodiment of the present invention;

[0041] Figure 4A-4D The present invention provides a process flow chart of preparing an n-type diamond epitaxial layer in a method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor provided in an embodiment of the present invention.

[0042] Reference numerals

[0043] 1-intrinsic diamond layer, 2-n-type diamond epitaxial layer, 2a-hydrogen terminal p-type conductive layer, 3a-source electrode, 3b-drain electrode, 4-gate dielectric, 5-gate electrode. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0045] In order to solve the problems that the current depletion-mode diamond field effect transistor devices have high power consumption and are difficult to meet the driving circuit design, and the enhancement-mode diamond field effect transistor devices with gate channel processing have poor characteristics, the embodiments of the present invention provide a diamond composite conductivity inversion channel enhancement field effect transistor and a preparation method thereof.

[0046] Below, firstly, a diamond composite conductivity inversion channel enhancement field effect transistor provided by an embodiment of the present invention is introduced.

[0047] like Figure 1 As shown, a diamond composite conductivity inversion channel enhanced field effect transistor provided by an embodiment of the present invention may include:

[0048] Intrinsic diamond layer 1, n-type diamond epitaxial layer 2, hydrogen-terminated p-type conductive layer 2a, source electrode 3a, drain electrode 3b, gate dielectric 4 and gate electrode 5; wherein,

[0049] An n-type diamond epitaxial layer 2 is disposed in a gate location region in the middle of the upper surface of the intrinsic diamond layer 1;

[0050] A hydrogen-terminated p-type conductive layer 2a is disposed in a region below the upper surface of the intrinsic diamond layer 1;

[0051] A source electrode 3a is disposed at one end of the upper surface of the intrinsic diamond layer 1;

[0052] The drain electrode 3b is arranged at the other end of the upper surface of the intrinsic diamond layer 1;

[0053] A gate dielectric 4 is disposed on the remaining area of ​​the upper surface of the intrinsic diamond layer 1 and the upper surface of the n-type diamond epitaxial layer 2;

[0054] The gate electrode 5 is disposed on the upper surface of the gate dielectric 4 corresponding to the gate position region.

[0055] Optionally, the n-type diamond epitaxial layer 2 may include:

[0056] Phosphorus, lithium, sodium doped diamond layer or selenium-phosphorus co-doped diamond layer.

[0057] The carrier surface density of the hydrogen-terminated p-type conductive layer 2a is 1×10 12 cm -2 -10 14 cm -2 , the carrier mobility is 50cm 2 / (V·S)-200cm 2 / (V·S).

[0058] Specifically, the n-type diamond epitaxial layer 2 and the hydrogen-terminated p-type conductive layer 2a constitute a channel under the gate.

[0059] In order to solve the problems of low carrier concentration, large channel on-resistance, small source-drain output current, etc. of enhancement-mode devices, the embodiment of the present invention uses an n-type diamond epitaxial layer and a hydrogen-terminated p-type conductive layer with p-type two-dimensional hole gas to conduct electricity in the channel under the gate. The n-type diamond epitaxial layer is a lightly doped diamond epitaxial layer. When the carrier concentrations of the two conductive layers are equivalent, when the gate voltage is positive, the two-dimensional hole gas of the hydrogen-terminated p-type conductive layer is repelled, and the n-type diamond epitaxial layer acts as a turned-off channel; when the gate voltage is zero, the two are offset and neutralized to obtain a turned-off channel under the gate; when the gate voltage is negative, the two-dimensional hole gas of the hydrogen-terminated p-type conductive layer is attracted, and the electrons of the n-type diamond epitaxial layer are repelled, thereby realizing a conductive channel with good conductivity, so that an enhancement-mode (normally off) diamond field effect transistor can be realized by using an inversion channel based on a diamond body doped conductive layer and surface conductivity, which has great significance for the logic circuit application and drive circuit design of future diamond field effect transistors.

[0060] Optionally, the material of the gate dielectric 4 may include Al 2 O 3 , thickness is 10nm-25nm.

[0061] The field effect transistor proposed in the embodiment of the present invention is implemented in the form of a composite conductance inversion channel based on diamond body doping body conductivity and surface conductance based on surface hole two-dimensional electron gas, and its under-gate channel is: the lower layer is an n-type diamond epitaxial layer, and the upper layer is a hydrogen-terminated p-type conductive layer; when different gate voltages are applied, the inversion channel formed by the n-type diamond epitaxial layer and the hydrogen-terminated p-type conductive layer realizes the function of turning on or off.

[0062] In a second aspect, corresponding to the above device embodiment, the present invention also provides a method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor, such as Figure 2 As shown, this may include:

[0063] S1, obtaining an intrinsic diamond layer 1 as a substrate.

[0064] The intrinsic diamond layer 1 may be a preformed product obtained directly, and the intrinsic diamond layer 1 may be used as a substrate after being cleaned accordingly.

[0065] S2 , growing an n-type diamond epitaxial layer 2 in the gate position region in the middle of the upper surface of the intrinsic diamond layer 1 .

[0066] For S2, Figure 3 As shown, this may include:

[0067] S21, depositing a protective layer on the upper surface of the intrinsic diamond layer 1, may include:

[0068] A protective layer is deposited on the upper surface of the intrinsic diamond layer 1 by electron beam evaporation or magnetron sputtering; wherein the material of the protective layer may include a titanium / gold alloy layer or a SiO 2 , with a thickness of 80-120 nm. The device after the protective layer obtained in step S21 is as follows Figure 4A shown.

[0069] S22, removing the protective layer on the gate location region in the middle of the upper surface of the intrinsic diamond layer 1, may include:

[0070] A layer of photoresist is evenly coated on the protective layer. The model of the photoresist can be AZ5214. It is dried at 100°C for 150 seconds. The gate position area in the middle of the upper surface of the intrinsic diamond layer 1 is exposed through the pattern shielding of the mask using an ultraviolet lithography machine. The exposure time is 3.3 seconds. Then, it is developed in a positive developer for 45 seconds to expose the exposed area. Then, it is exposed in a KI / I 2 The device is immersed in the solution and BOE solution for 6-10s and 3-6 minutes respectively to avoid large lateral corrosion, so as to obtain a protective layer in the area where the gate is exposed. The cleaning material is immersed in acetone to remove the photoresist. The device is as shown in FIG. Figure 4B shown.

[0071] S23 , growing an n-type diamond epitaxial layer 2 on the upper surface of the intrinsic diamond layer 1 under preset chamber conditions.

[0072] Specifically, in the gate position area in the middle of the upper surface of the intrinsic diamond layer 1, a microwave plasma chemical vapor deposition MPCVD device is used to grow an n-type diamond epitaxial layer 2, and the specific chamber conditions are hydrogen flow rate 200-400sccm, chamber pressure 140-160mbar, temperature 700-1000°C, methane flow rate 5-20sccm, oxygen flow rate 0.2-0.8sccm, and processing time 5-15min. The phosphorus-doped diamond thickness is 100-300nm. The device obtained by step S23 is as follows Figure 4C shown.

[0073] S24, removing the protective layer on the upper surface of the remaining intrinsic diamond layer 1.

[0074] Specifically, the device obtained in step S23 is placed in KI / I 2 The device is immersed in a solution and a BOE (Buffered Oxide Etch) solution to completely remove the protective layer. Figure 4D shown.

[0075] S3 , performing hydrogen termination treatment on the upper surface of the intrinsic diamond layer 1 , and generating a hydrogen-terminated p-type conductive layer 2 a in a region below the upper surface of the intrinsic diamond layer 1 .

[0076] For S3, this can include:

[0077] In the MPCVD equipment, a hydrogen-terminated p-type conductive layer 2a is generated in the area below the upper surface of the intrinsic diamond layer 1 by preset chamber conditions; wherein the preset chamber conditions include: hydrogen flow rate: 200sccm-400sccm, chamber pressure: 140mbar-160mbar, microwave power: 2kW-2.5kW, temperature: 650℃-850℃, methane flow rate: 5sccm-20sccm, and processing time: 10min-45min.

[0078] The carrier surface density of the hydrogen-terminated p-type conductive layer 2a obtained by step S3 can be 1×10 12 cm -2 -10 14 cm -2 , the carrier mobility can be 50cm 2 / (V·S)-200cm 2 / (V· S).

[0079] After completing step S3, the n-type diamond epitaxial layer and the hydrogen-terminated p-type conductive layer with p-type two-dimensional hole gas can form a gate-under-channel, and the gate-under-channel is: the lower layer is the n-type diamond epitaxial layer, and the upper layer is the p-type two-dimensional hole gas conductive layer; when different gate voltages are applied, the inversion channel formed by the n-type diamond epitaxial layer and the surface p-type two-dimensional hole gas conductive layer can realize the function of turning on or off.

[0080] S4, depositing a source electrode 3a and a drain electrode 3b at both ends of the upper surface of the intrinsic diamond layer 1 respectively.

[0081] For S4, this may include:

[0082] A 100 nm gold (Au) thin film layer is deposited on the diamond surface with a hydrogen-terminated p-type conductive layer 2a by thermal evaporation, and a photoresist is evenly coated. The photoresist model can be AZ6112, and dried at 90°C for 90s. The non-source and drain pattern positions on the mask are exposed using an ultraviolet photolithography machine, and then immersed in KI / I 2 After 6-10 seconds in the solution, the gold film layer at the non-source and drain positions is removed, leaving the gold film layer at the source and drain positions as the source electrode 3a and the drain electrode 3b respectively.

[0083] S5, preparing a gate dielectric 4 on the remaining area of ​​the upper surface of the intrinsic diamond layer 1 and the upper surface of the n-type diamond epitaxial layer 2, may include:

[0084] A gate dielectric (4) is prepared on the remaining area of ​​the upper surface of the intrinsic diamond layer (1) and the upper surface of the n-type diamond epitaxial layer (2) by an atomic layer deposition method under preset process conditions; wherein the preset process conditions are a process temperature of 150° C. to 400° C., a thickness of the gate dielectric (4) of 10 nm to 25 nm, and a material of the gate dielectric 4 may include Al 2 O 3 .

[0085] S6, preparing a gate electrode 5 on the upper surface of the gate dielectric 4 corresponding to the gate position area, may include:

[0086] The deposition area is distributed in all areas except the source and drain position area, which can achieve the effect of passivation, protect the hydrogen terminal p-type conductive layer, and improve the stability of the device. A layer of photoresist is uniformly coated on the surface of the diamond layer with the gate dielectric 4. The photoresist model can be AZ6130, and it is dried at 90°C for 90s. A pattern is left in the preset gate position area through the mask gate pattern using an ultraviolet lithography machine, and then aluminum (Al) is deposited by electron beam evaporation with a thickness of 100nm to obtain a gate electrode 5.

[0087] The field effect tube provided in the embodiment of the present invention uses an n-type diamond epitaxial layer and a hydrogen-terminated p-type conductive layer with a p-type two-dimensional hole gas to form a channel under the gate. When a positive gate voltage is applied to the gate electrode in the enhanced field effect tube proposed by the present invention, the two-dimensional hole gas in the channel under the gate conducts electricity, the holes are repelled and exhausted, and the channel is turned off; when the gate electrode is at zero gate voltage, the electrons in the n-type diamond epitaxial layer and the holes in the hydrogen-terminated p-type conductive layer are offset and neutralized when the concentrations are equivalent, and the channel is turned off; when a negative gate voltage is applied to the gate electrode, the holes in the hydrogen-terminated p-type conductive layer are attracted, and the electrons in the n-type diamond epitaxial layer are repelled, forming an inversion channel, and the channel is turned on, thereby realizing a conductive channel with better conductivity. The source-drain current formed in the hydrogen-terminated p-type conductive layer can increase the carrier concentration under the gate of the field effect tube, increase the current density, reduce the channel resistance, and enhance the gate control capability.

[0088] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A diamond composite conductivity inversion channel enhancement field effect transistor, characterized in that: include: An intrinsic diamond layer (1), an n-type diamond epitaxial layer (2), a hydrogen-terminated p-type conductive layer (2a), a source electrode (3a), a drain electrode (3b), a gate dielectric (4) and a gate electrode (5); wherein: The n-type diamond epitaxial layer (2) is arranged in a gate position region in the middle of the upper surface of the intrinsic diamond layer (1); The hydrogen-terminated p-type conductive layer (2a) is arranged in a region below the upper surface of the intrinsic diamond layer (1); The source electrode (3a) is arranged at one end of the upper surface of the intrinsic diamond layer (1); The drain electrode (3b) is arranged at the other end of the upper surface of the intrinsic diamond layer (1); The gate dielectric (4) is arranged on the remaining area of ​​the upper surface of the intrinsic diamond layer (1) and the upper surface of the n-type diamond epitaxial layer (2); The gate electrode (5) is arranged on the upper surface of the gate dielectric (4) corresponding to the gate position area.

2. The diamond composite conductivity inversion channel enhanced field effect transistor according to claim 1, characterized in that: The n-type diamond epitaxial layer (2) comprises: Phosphorus, lithium, sodium doped diamond layer or selenium-phosphorus co-doped diamond layer.

3. The diamond composite conductivity inversion channel enhanced field effect transistor according to claim 1, characterized in that: The n-type diamond epitaxial layer (2) and the hydrogen-terminated p-type conductive layer (2a) form a channel under the gate.

4. The diamond composite conductivity inversion channel enhanced field effect transistor according to claim 1, characterized in that: The carrier surface density of the hydrogen terminal p-type conductive layer (2a) is 1×10 12 cm -2 -10 14 cm -2 , the carrier mobility is 50cm 2 / (V·S)-200cm 2 / (V·S).

5. The diamond composite conductivity inversion channel enhanced field effect transistor according to claim 1, characterized in that: The material of the gate dielectric (4) includes Al2O3 and has a thickness of 10nm-25nm.

6. A method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor, characterized in that: include: Obtaining an intrinsic diamond layer (1) as a substrate; Growing an n-type diamond epitaxial layer (2) in a gate location region in the middle of the upper surface of the intrinsic diamond layer (1); Performing a hydrogen termination treatment on the upper surface of the intrinsic diamond layer (1) to generate a hydrogen-terminated p-type conductive layer (2a) in a region below the upper surface of the intrinsic diamond layer (1); A source electrode (3a) and a drain electrode (3b) are deposited at two ends of the upper surface of the intrinsic diamond layer (1); Preparing a gate dielectric (4) on the remaining area of ​​the upper surface of the intrinsic diamond layer (1) and the upper surface of the n-type diamond epitaxial layer (2); A gate electrode (5) is prepared on the upper surface of the gate dielectric (4) corresponding to the gate position area.

7. The method for preparing a diamond composite conductivity inversion channel enhanced field effect transistor according to claim 6, characterized in that: Growing an n-type diamond epitaxial layer (2) in a gate position region in the middle of the upper surface of the intrinsic diamond layer (1), comprising: Depositing a protective layer on the upper surface of the intrinsic diamond layer (1); Removing the protective layer on the gate location area in the middle of the upper surface of the intrinsic diamond layer (1); Under preset chamber conditions, growing an n-type diamond epitaxial layer (2) on the upper surface of the intrinsic diamond layer (1); The remaining protective layer on the upper surface of the intrinsic diamond layer (1) is removed.

8. The method for preparing a diamond composite conductivity inversion channel enhanced field effect transistor according to claim 7, characterized in that: A protective layer is deposited on the upper surface of the intrinsic diamond layer (1), comprising: A protective layer is deposited on the upper surface of the intrinsic diamond layer (1) by electron beam evaporation or magnetron sputtering; wherein the material of the protective layer includes a titanium / gold alloy layer or SiO2, and the thickness is 80-120nm.

9. The method for preparing a diamond composite conductivity inversion channel enhancement field effect transistor according to claim 6, characterized in that: The upper surface of the intrinsic diamond layer (1) is subjected to hydrogen termination treatment to generate a hydrogen-terminated p-type conductive layer (2a) in a region below the upper surface of the intrinsic diamond layer (1), comprising: In an MPCVD device, a hydrogen-terminated p-type conductive layer (2a) is generated in a region below the upper surface of the intrinsic diamond layer (1) by preset chamber conditions; wherein the preset chamber conditions include: hydrogen flow rate: 200sccm-400sccm, chamber pressure: 140mbar-160mbar, microwave power: 2kW-2.5kW, temperature: 650°C-850°C, methane flow rate: 5sccm-20sccm, and processing time: 10min-45min.

10. The method for preparing a diamond composite conductivity inversion channel enhanced field effect transistor according to claim 6, characterized in that: A gate dielectric (4) is prepared on the remaining area of ​​the upper surface of the intrinsic diamond layer (1) and the upper surface of the n-type diamond epitaxial layer (2), comprising: A gate dielectric (4) is prepared on the remaining area of ​​the upper surface of the intrinsic diamond layer (1) and the upper surface of the n-type diamond epitaxial layer (2) by an atomic layer deposition method under preset process conditions; wherein the preset process conditions are a process temperature of 150° C. to 400° C. and a thickness of the gate dielectric (4) of 10 nm to 25 nm.

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