An improved hydrogen-terminated diamond field effect transistor and method of making the same

Abstract

The application belongs to the technical field of semiconductor devices, and discloses an improved hydrogen-terminated diamond field effect transistor and a preparation method thereof; wherein, in the improved hydrogen-terminated diamond field effect transistor, a single crystal diamond film is homogeneously epitaxied on a single crystal diamond substrate, and a diamond conductive channel is formed on the surface of the single crystal diamond film; a source electrode and a drain electrode are arranged on the surface of the diamond conductive channel; a dielectric layer is deposited on the diamond conductive channel between the source electrode and the drain electrode, and a gate electrode is arranged on the dielectric layer; an oxygen-terminated isolation region is formed on the exposed area of the single crystal diamond film outside the diamond conductive channel between the source electrode and the drain electrode; and the surface of the diamond conductive channel is a composite terminal of hydrogen termination and germanium termination. The technical scheme can solve the problems of poor surface conductance stability, high interface state density and low carrier mobility of the hydrogen-terminated diamond field effect transistor.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, specifically the field of diamond field-effect transistors, and particularly relates to an improved hydrogen-terminated diamond field-effect transistor and its fabrication method. Background Technology

[0002] As an ultra-wide bandgap semiconductor, diamond possesses excellent properties such as a wide bandgap, high breakdown field strength, high hole and electron mobility, high thermal conductivity, and high quality factor, as detailed in Table 1. These superior properties enable diamond-based electronic devices to operate safely and stably even under harsh conditions such as high temperature, high pressure, high power, high frequency, and strong radiation. Notably, diamond boasts a thermal conductivity as high as 22 W / cm·K, a level that promises to overcome the technical bottleneck of the "self-heating effect" in other semiconductors. Furthermore, its breakdown field strength reaches 20 MV / cm, offering a potential solution to the "avalanche breakdown" problem in traditional semiconductor materials. Additionally, diamond's high Johnson, Keyes, and Baliga factors enable the fabrication of high-power, high-frequency electronic devices. Therefore, diamond is hailed by the industry as the "ultimate semiconductor."

[0003] Table 1. Comparison of properties of diamond with other semiconductor materials

[0004]

[0005]

[0006] The high activation energies of boron and phosphorus, commonly used dopants in p-type and n-type diamond semiconductors, significantly hinder the application and development of diamond-based electronic devices. Fortunately, hydrogen-terminated diamond can generate two-dimensional hole gas near its surface, providing a new solution for the development of diamond field-effect transistors (FETs). However, hydrogen-terminated diamond surfaces are not conductive under vacuum conditions; they only exhibit conductivity when exposed to air. In other words, hydrogen termination and air adsorbates are necessary conditions for the conductivity of hydrogen-terminated diamond; neither can be omitted. These characteristics determine the unstable surface conductivity of hydrogen-terminated diamond FETs. Furthermore, air adsorbates cause surface impurity scattering, leading to a high interface state density, which severely limits device characteristics such as carrier mobility. Summary of the Invention

[0007] The purpose of this invention is to provide an improved hydrogen-terminated diamond field-effect transistor and its fabrication method, so as to solve the technical problems of poor surface conductivity stability, high interface state density and low carrier mobility in the prior art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an improved hydrogen-terminated diamond field-effect transistor, comprising: a single-crystal diamond substrate, a single-crystal diamond thin film, a diamond conductive channel, a source electrode, a drain electrode, an oxygen-terminated isolation region, a dielectric layer, and a gate electrode; wherein,

[0010] The single-crystal diamond film is homoepitaxially formed on the single-crystal diamond substrate, and the diamond conductive channel is formed on the surface of the single-crystal diamond film.

[0011] The source electrode and the drain electrode are disposed on the surface of the diamond conductive channel, and the source electrode and the drain electrode form an ohmic contact with the diamond conductive channel; the dielectric layer is deposited on the source electrode, the drain electrode, and the diamond conductive channel between the source electrode and the drain electrode, and the gate electrode is disposed on the dielectric layer; the exposed area of ​​the single crystal diamond film outside the diamond conductive channel between the source electrode, the drain electrode, and the source electrode and the drain electrode forms an oxygen termination isolation region;

[0012] The surface of the diamond conductive channel is a composite terminal of hydrogen terminals and germanium terminals.

[0013] A further improvement of the present invention is that,

[0014] All areas of the surface of the diamond conductive channel are composite terminals of hydrogen terminals and germanium terminals.

[0015] Alternatively, the area of ​​the surface of the diamond conductive channel below the gate electrode is a composite terminal of hydrogen and germanium terminals, and the remaining area is a hydrogen terminal.

[0016] Alternatively, the surface of the diamond conductive channel may have a composite terminal consisting of hydrogen and germanium terminals in the region between the source electrode and the drain electrode, with the remaining region being hydrogen-terminated.

[0017] A further improvement of the present invention is that the single-crystal diamond film is prepared by CVD technology, with a root mean square surface roughness ≤1nm and a Raman curve half-width ≤5cm. -1 The XRD rocking curve has a half-width of ≤50 arcsec and a film thickness of 0.2–1 μm.

[0018] A further improvement of the present invention is that the carrier concentration of the diamond conductive channel is ≥10. 12 cm -2 Carrier mobility ≥200cm 2 / V·s.

[0019] A further improvement of the present invention is that the material of the source electrode is Au, Pt, Ir, Pd or Ti.

[0020] A further improvement of the present invention is that the material of the drain electrode is Au, Pt, Ir, Pd or Ti.

[0021] A further improvement of the present invention is that the material of the gate electrode is Ge, Au, Pt, Ir, Pd, Al, Zr, Mo or Ti.

[0022] A further improvement of the present invention is that the resistance of the oxygen terminal isolation region is ≥1 GΩ.

[0023] A further improvement of the present invention is that the dielectric constant of the dielectric layer is ≥3.9.

[0024] In a second aspect, the present invention provides an improved method for fabricating a hydrogen-terminated diamond field-effect transistor as described in the first aspect, comprising the following steps:

[0025] A single-crystal diamond film was obtained by homoepitaxial generation on a cleaned and dried single-crystal diamond substrate.

[0026] Hydrogenation treatment of single-crystal diamond films yields diamond conductive channels containing carbon-hydrogen bonds.

[0027] A diamond conductive channel containing carbon-hydrogen bonds is obtained by treating a first selected region with germanium plasma to obtain a diamond conductive channel with a composite terminal consisting of hydrogen and germanium terminals on its surface; or, a germanium thin film is deposited in the first selected region of the diamond conductive channel containing carbon-hydrogen bonds using a coating technique and then annealed in a vacuum environment or reacted in a high-temperature reducing atmosphere, followed by removal of the germanium thin film using a solution to obtain a diamond conductive channel with a composite terminal consisting of hydrogen and germanium terminals on its surface; or, a germanium oxide thin film is deposited in the first selected region of the diamond conductive channel containing carbon-hydrogen bonds using a coating technique and then annealed in a vacuum environment or reacted in a high-temperature reducing atmosphere, followed by removal of the germanium oxide thin film using a solution to obtain a diamond conductive channel with a composite terminal consisting of hydrogen and germanium terminals on its surface.

[0028] Source and drain electrodes are fabricated in the second and third selected regions on the surface of a diamond conductive channel with a composite terminal of hydrogen and germanium terminals, respectively, and both the source and drain electrodes form ohmic contacts with the diamond conductive channel. The exposed area of ​​the single-crystal diamond film outside the diamond conductive channel between the source and drain electrodes is treated to form an oxygen-terminated isolation region to achieve electrical isolation of the device.

[0029] An improved hydrogen-terminated diamond field-effect transistor containing carbon-germanium bonds and carbon-hydrogen bonds is obtained by depositing a dielectric layer on the source electrode, drain electrode, and diamond conductive channel between the source electrode and drain electrode, and fabricating a gate electrode on the dielectric layer.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention discloses an improved hydrogen-terminated diamond field-effect transistor (DFFET). Addressing the shortcomings of hydrogen-terminated DFFETs, the hydrogen termination on the surface of the diamond conductive channel is improved to a composite termination of hydrogen and germanium (i.e., a diamond conductive channel containing carbon-germanium bonds and carbon-hydrogen bonds), thus enabling the modulation of the electrical characteristics of the DFFET. Explained, germanium, like hydrogen, has a lower electronegativity than carbon (specifically, germanium has an electronegativity of 2.01, hydrogen 2.1, and carbon 2.55), implying that the germanium-terminated diamond structure also possesses a negative electron affinity and potential p-type conductivity. Further explained, the weaker carbon-hydrogen bond energy and stronger carbon-germanium bond energy contribute to the good stability of the improved composite-terminated diamond containing hydrogen and germanium terminations. Simultaneously, the unsaturated dangling bonds of tetravalent germanium can bond with the dielectric layer, resulting in lower interface states and higher mobility in the DFFET, thereby optimizing the DFFET performance. In summary, the improved hydrogen-terminated and germanium-terminated composite-terminated diamond field-effect transistor of this invention retains the advantages of hydrogen-terminated diamond field-effect transistors, while also improving the stability of surface conductivity, reducing the interface state density of the device, and increasing carrier mobility. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of an improved hydrogen-terminated diamond field-effect transistor in an embodiment of the present invention.

[0034] Figure 2 yes Figure 1 The above-view schematic diagram of the embodiment is shown.

[0035] Figure 3 This is a schematic flowchart of an improved method for fabricating a hydrogen-terminated diamond field-effect transistor in an embodiment of the present invention.

[0036] The annotations in the figure are explained as follows:

[0037] 1. Single-crystal diamond substrate; 2. Single-crystal diamond thin film; 3. Diamond conductive channel; 4. Source electrode; 5. Drain electrode; 6. Oxygen-terminated isolation region; 7. Dielectric layer; 8. Gate electrode. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0039] Please see Figure 1 and Figure 2 In this embodiment of the invention, an improved hydrogen-terminated diamond field-effect transistor is provided, comprising: a single-crystal diamond substrate 1, a single-crystal diamond thin film 2, a diamond conductive channel 3, a source electrode 4, a drain electrode 5, an oxygen-terminated isolation region 6, a dielectric layer 7, and a gate electrode 8; wherein,

[0040] A single-crystal diamond film 2 is homoepitaxially formed on the top outer wall of the single-crystal diamond substrate 1, and the diamond conductive channel 3 is formed on the surface of the single-crystal diamond film 2.

[0041] The surface of the diamond conductive channel 3 is provided with a source electrode 4 and a drain electrode 5. The exposed area of ​​the single crystal diamond film outside the diamond conductive channel between the source electrode 4, the drain electrode 5 and the two forms an oxygen terminal isolation region 6. The dielectric layer 7 is deposited on the source electrode 4, the drain electrode 5 and the diamond conductive channel between the two. The gate electrode 8 is provided on the dielectric layer 7.

[0042] The surface of the diamond conductive channel 3 is a composite terminal of hydrogen and germanium terminals (i.e., the diamond conductive channel 3 contains carbon-germanium bonds and carbon-hydrogen bonds).

[0043] In a specific example, the composite terminal may be presented in a block form; for example, the composite terminal may be located below the gate electrode 8 on the single-crystal diamond film 2, with the remaining positions being hydrogen terminals; or, it may be located between the source electrode 4 and the drain electrode 5 on the single-crystal diamond film 2 (excluding the source electrode 4 and the drain electrode 5), with the remaining positions being hydrogen terminals; or, the composite terminal may also be located between the source electrode 4 and the drain electrode 5 on the single-crystal diamond film 2 (including the source electrode 4 and the drain electrode 5).

[0044] The relatively weak carbon-hydrogen bond energy and the relatively strong carbon-germanium bond energy give the improved composite-terminated diamond, which includes hydrogen and germanium terminals, good stability. Furthermore, the unsaturated dangling bonds of tetravalent germanium can bond with the dielectric layer, resulting in lower interface states and higher mobility in the diamond field-effect transistor, thereby optimizing the transistor's performance.

[0045] In one embodiment of the present invention, the single-crystal diamond substrate 1 is prepared by chemical vapor deposition (CVD) or high-temperature high-pressure (HTHP) technology, and a single-crystal diamond film 2 is homoepitaxially formed on its top outer wall. Exemplarily, the single-crystal diamond film 2 is grown using CVD technology, with a root-mean-square surface roughness ≤1 nm and a Raman curve half-maximum width ≤5 cm. -1 The XRD rocking curve has a half-width of ≤50 arcsec and a film thickness of 0.2–1 μm.

[0046] In one embodiment of the present invention, the carrier concentration of the diamond conductive channel 3 is ≥10. 12 cm -2 Carrier mobility ≥200cm 2 / V·s.

[0047] In one embodiment of the present invention, the source electrode 4 and the drain electrode 5 are good conductors and form ohmic contacts with the single crystal diamond film 2 directly or after annealing. The materials are Au, Pt, Ir, Pd or Ti, and can be prepared by a variety of different methods, including but not limited to magnetron sputtering, thermal evaporation, electron beam evaporation, etc.

[0048] In one embodiment of the present invention, the resistance of the oxygen terminal isolation region 6 is ≥1 GΩ, which can be prepared by ozone treatment technology or oxygen plasma treatment technology.

[0049] In one embodiment of the present invention, the dielectric layer 7 is a material with a high dielectric constant, ≥3.9, and can be prepared by a variety of different methods, including but not limited to magnetron sputtering, thermal evaporation, electron beam evaporation, and atomic layer deposition.

[0050] In one embodiment of the present invention, the gate electrode 8 is a good conductor, and its material is Ge, Au, Pt, Ir, Pd, Al, Zr, Mo or Ti. It can be prepared by a variety of different methods, including but not limited to magnetron sputtering, thermal evaporation, electron beam evaporation, etc.

[0051] The improved hydrogen-terminated diamond field-effect transistor disclosed in this invention can enhance the stability of the device surface conductivity, reduce the interface state density, and improve carrier mobility. Germanium plasma processing methods include, but are not limited to, glow discharge, high-voltage pulse, and microwave plasma. Germanium thin films or germanium oxide thin films can be prepared using various methods, including but not limited to magnetron sputtering, thermal evaporation, electron beam evaporation, and atomic layer deposition.

[0052] Please see Figure 3 In this embodiment of the invention, an improved method for fabricating a hydrogen-terminated diamond field-effect transistor is provided, which is carried out in the following steps:

[0053] Step 1) Clean the single-crystal diamond substrate and dry it;

[0054] Step 2) Homogeneously epitaxial single-crystal diamond thin films are formed on single-crystal diamond substrates using microwave plasma chemical vapor deposition (MPCVD) equipment;

[0055] Step 3) Using an MPCVD device, hydrogenate the single-crystal diamond film to obtain a diamond conductive channel containing carbon-hydrogen bonds; or use germanium plasma treatment, or use a coating technology to deposit a germanium film and then anneal it in a vacuum environment or react it in a high-temperature reducing atmosphere, or use a coating technology to deposit a germanium oxide film and then anneal it in a vacuum environment or react it in a high-temperature reducing atmosphere. For the method of depositing germanium film or germanium oxide film, the film still needs to be removed by solution to expose the improved hydrogen-terminated diamond conductive channel (i.e., forming a composite terminal diamond conductive channel containing carbon-germanium bonds and carbon-hydrogen bonds on the surface of the single-crystal diamond film).

[0056] Step 4) Using photolithography, deposition and lift-off techniques, source and drain electrodes are fabricated on the surface of the diamond conductive channel and form ohmic contacts with the single-crystal diamond film.

[0057] Step 5) Using a photoresist mask, an oxygen terminal isolation region is formed in the exposed area of ​​the single crystal diamond film outside the diamond conductive channel between the source electrode and the drain electrode by ultraviolet ozone treatment technology or oxygen plasma treatment technology to perform electrical isolation of the device.

[0058] Step 6) Deposit a dielectric layer on the source electrode, drain electrode and the diamond conductive channel between them using photolithography, deposition and lift-off techniques.

[0059] Step 7) The gate electrode is fabricated on the dielectric layer using photolithography, deposition and lift-off techniques to complete the fabrication of a typical improved hydrogen-terminated diamond field-effect transistor containing carbon-germanium bonds and carbon-hydrogen bonds. Specific Implementation Example 1

[0061] Please see Figures 1 to 3An improved method for fabricating a hydrogen-terminated diamond field-effect transistor according to an embodiment of the present invention includes the following steps:

[0062] 1) The HTHP single crystal diamond substrate was cleaned using a diamond cleaning process and dried with nitrogen gas for later use.

[0063] 2) A single-crystal diamond film was deposited on a single-crystal diamond substrate using microwave plasma chemical deposition (MPCVD). The total gas flow rate was 500 sccm, the CH4 / H2 ratio was 1%, the plasma power was 1 kW, the temperature was 900℃, the pressure was 100 Torr, and the processing time was 30 min. The resulting single-crystal diamond film had a thickness of 0.2 μm, a root mean square surface roughness of 0.5 nm, and a Raman curve half-width of 3 cm. -1 The half-peak width of the XRD rocking curve is 50 arcsec.

[0064] 3) Set the CH4 flow rate to 0 sccm and maintain the hydrogen flow rate at 50 sccm to hydrogenate the grown single-crystal diamond film for 20 min to obtain a single-crystal diamond conductive channel containing carbon-hydrogen bonds; use an electron beam evaporation device to evacuate the vacuum to 5 × 10⁻⁶. -4 A 5 nm germanium thin film was deposited at a deposition rate of 0.05 nm / s using a rapid annealing furnace under vacuum at 600 °C for 20 min, yielding a composite-terminated diamond conductive channel containing both carbon-germanium and carbon-hydrogen bonds. The sample was then removed, and the germanium film was removed using potassium chloride solution, resulting in an improved hydrogen-terminated diamond conductive channel with a carrier concentration of 10-1. 13 cm -2 Mobility 200cm 2 / V·s.

[0065] 4) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, preheat at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporation apparatus and evacuate to a vacuum of 5×10⁻⁶. -4 Pa, deposition rate 0.1 nm / s, deposited metal Au 150 nm. After soaking in acetone solution for 5 min, the source and drain electrodes were obtained.

[0066] 5) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with photoresist AZ5214, pre-bake at 95℃ for 90s, expose to UV light for 8s using a mask, and develop with ZX-238 for 45s. Using the photoresist mask, treat with oxygen plasma for 5min (oxygen flow rate 50sccm, plasma 100W) to form an oxygen-terminated isolation region. Remove the sample and immerse it in acetone solution for 5min to remove the photoresist.

[0067] 6) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, pre-bake at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporator and evacuate to a vacuum of 5×10⁻⁶. -4 At a deposition rate of 0.1 nm / s, a SiN layer of 30 nm was deposited. The layer was then peeled off after immersion in acetone solution for 5 min.

[0068] 7) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, pre-bake at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporation apparatus and evacuate to a vacuum of 5×10⁻⁶. -4 At a deposition rate of 0.2 nm / s, 150 nm of Al metal was deposited. The electrode was then stripped by immersion in acetone solution for 5 min to obtain the gate electrode. Specific Implementation Example 2

[0070] Please see Figures 1 to 3 An improved method for fabricating a hydrogen-terminated diamond field-effect transistor according to an embodiment of the present invention includes the following steps:

[0071] 1) The CVD single crystal diamond substrate was first cleaned with inorganic and then with organic cleaning using a diamond cleaning process, and then dried with nitrogen gas for later use.

[0072] 2) A single-crystal diamond film was deposited on a single-crystal diamond substrate using microwave plasma chemical deposition (MPCVD). The total gas flow rate was 500 sccm, the CH4 / H2 ratio was 1%, the plasma power was 1 kW, the temperature was 950℃, the pressure was 100 Torr, and the processing time was 50 min. The resulting single-crystal diamond film had a thickness of 0.3 μm, a root mean square surface roughness of 0.5 nm, and a Raman curve half-width of approximately 3 cm. -1 The half-width of the XRD rocking curve is less than 50 arcsec.

[0073] 3) Set the CH4 flow rate to 0 sccm and maintain the hydrogen flow rate at 50 sccm to hydrogenate the grown single-crystal diamond film for 20 min to obtain a single-crystal diamond conductive channel containing carbon-hydrogen bonds.

[0074] 4) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, preheat at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporation apparatus and evacuate to a vacuum of 5×10⁻⁶. -4At a deposition rate of 0.2 nm / s, Ti / Pt / Au layers of 50 / 50 / 50 nm were deposited sequentially. The layers were then stripped by immersion in acetone solution for 5 min to obtain the source and drain electrodes. Annealing was performed at 600 °C for 5 min under a nitrogen atmosphere to form excellent ohmic contacts.

[0075] 5) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with photoresist AZ5214, pre-bake at 95℃ for 90s, expose to UV light for 8s using a mask, and develop with ZX-238 for 45s. Using the photoresist mask, oxidize the exposed area with a UV ozone treatment machine for 20min to form an oxygen-terminated isolation zone for device isolation. Remove the sample and immerse it in acetone solution for 5min to remove the photoresist, thus completing device isolation.

[0076] 6) Clean the sample with acetone, alcohol, and deionized water, and dry it; spin-coat the sample surface with AZ5214 photoresist, pre-bake at 95℃ for 90s, expose to ultraviolet light using a mask for 8s, and develop with ZX-238 for 45s; use an electron beam evaporator to evaporate to a vacuum of 5×10⁻⁶. -4 At a deposition rate of 0.3 nm / s, a 100 nm layer of Al metal was deposited as a mask, and the photoresist was removed by immersion in acetone solution for 5 min. Using patterned Al metal as a mask, the vacuum was reduced to 5 × 10⁻⁶ using an electron beam evaporation apparatus. -4 At a deposition rate of 0.05 nm / s, a 5 nm germanium oxide film was deposited. Annealing was performed in a rapid annealing furnace under vacuum at 600 °C for 20 min. The sample was then removed, and the germanium oxide film and Al mask were removed using HCl solution to obtain a patterned composite-terminated diamond conductive channel containing carbon-germanium and carbon-hydrogen bonds, with a carrier concentration of 10. 13 cm -2 The migration rate is 200cm. 2 / V·s.

[0077] 7) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, pre-bake at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporation apparatus and evacuate to a vacuum of 5×10⁻⁶. -4 At a deposition rate of 0.1 nm / s, a SiN layer of 30 nm was deposited. The layer was then peeled off after immersion in acetone solution for 5 min.

[0078] 8) Clean the sample with acetone, alcohol, and deionized water, and dry it. Spin-coat the sample surface with AZ5214 photoresist, preheat at 95°C for 90 seconds, expose to UV light using a mask for 8 seconds, and develop with ZX-238 for 45 seconds. Place the sample in an electron beam evaporation apparatus and evacuate to a vacuum of 5×10⁻⁶. -4At a deposition rate of 0.3 nm / s, 150 nm of Au metal was deposited. The electrode was then stripped by immersion in acetone solution for 5 minutes to obtain the gate electrode.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An improved hydrogen-terminated diamond field effect transistor, characterized in that, Comprise: A single crystal diamond substrate (1), a single crystal diamond film (2), a diamond conductive channel (3), a source electrode (4), a drain electrode (5), an oxygen terminal isolation region (6), a dielectric layer (7) and a gate electrode (8); wherein, The single crystal diamond film (2) is homogeneously epitaxial on the single crystal diamond substrate (1), and the surface of the single crystal diamond film (2) forms the diamond conductive channel (3); The surface of the diamond conductive channel (3) is provided with the source electrode (4) and the drain electrode (5), and the source electrode (4), the drain electrode (5) and the diamond conductive channel (3) form an ohmic contact; the source electrode (4), the drain electrode (5) and the diamond conductive channel between the source electrode (4) and the drain electrode (5) are deposited with the dielectric layer (7), and the dielectric layer (7) is provided with the gate electrode (8); the exposed region of the single crystal diamond film outside the source electrode (4), the drain electrode (5) and the diamond conductive channel between the source electrode (4) and the drain electrode (5) forms the oxygen terminal isolation region (6); Wherein, the surface of the diamond conductive channel (3) is a composite terminal of hydrogen terminal and germanium terminal.

2. The improved hydrogen terminal diamond field effect transistor according to claim 1, wherein, All regions of the surface of the diamond conductive channel (3) are composite terminals of hydrogen terminal and germanium terminal; Or, the regions of the surface of the diamond conductive channel (3) below the gate electrode (8) are composite terminals of hydrogen terminal and germanium terminal, and the remaining regions are hydrogen terminals; Or, the regions of the surface of the diamond conductive channel (3) between the source electrode (4) and the drain electrode (5) are composite terminals of hydrogen terminal and germanium terminal, and the remaining regions are hydrogen terminals.

3. An improved hydrogen-terminated diamond field effect transistor as claimed in claim 1, wherein, The single crystal diamond film (2) is prepared by CVD technology, with root mean square surface roughness ≤1nm, Raman curve half-peak width ≤5cm -1 , XRD rocking curve half-peak width ≤50 arcsec, and film thickness of 0.2-1μm.

4. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The carrier concentration of the diamond conductive channel (3) is ≥ 10 12 cm -2 -1 2 , and the carrier mobility is ≥ 200 cm / V·s.

5. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The material of the source electrode (4) is Au, Pt, Ir, Pd or Ti.

6. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The material of the drain electrode (5) is Au, Pt, Ir, Pd or Ti.

7. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The material of the gate electrode (8) is Ge, Au, Pt, Ir, Pd, Al, Zr, Mo or Ti.

8. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The resistance of the oxygen terminal isolation region (6) is ≥1GΩ.

9. An improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The dielectric constant of the dielectric layer (7) is ≥3.

9.

10. A method of fabricating an improved hydrogen-terminated diamond field effect transistor as defined in claim 1, wherein, The method comprises the following steps: Homogeneously epitaxial single crystal diamond film is obtained on the cleaned and dried single crystal diamond substrate; Hydrogenation treatment is performed on the single crystal diamond film to obtain a diamond conductive channel containing carbon-hydrogen bonds; The first selected region of the diamond conductive channel containing carbon-hydrogen bond is treated by germanium plasma to obtain the diamond conductive channel with a surface of hydrogen terminal and germanium terminal composite terminal; or, the first selected region of the diamond conductive channel containing carbon-hydrogen bond is deposited with germanium film by coating technology and treated by annealing in vacuum or reaction in high-temperature reducing atmosphere, and then the diamond conductive channel with a surface of hydrogen terminal and germanium terminal composite terminal is obtained by removing the germanium film with solution; or, the first selected region of the diamond conductive channel containing carbon-hydrogen bond is deposited with germanium oxide film by coating technology and treated by annealing in vacuum or reaction in high-temperature reducing atmosphere, and then the diamond conductive channel with a surface of hydrogen terminal and germanium terminal composite terminal is obtained by removing the germanium oxide film with solution; The source electrode and the drain electrode are prepared respectively on the second selected region and the third selected region of the surface of the diamond conductive channel with a surface of hydrogen terminal and germanium terminal composite terminal, and the source electrode and the drain electrode are both in ohmic contact with the diamond conductive channel; The single-crystal diamond film bare region outside the diamond conductive channel between the source electrode and the drain electrode is treated to form an oxygen terminal isolation region, so as to realize electrical isolation of the device; The dielectric layer is deposited on the source electrode, the drain electrode and the diamond conductive channel between the source electrode and the drain electrode, and the gate electrode is prepared on the dielectric layer, so as to obtain the improved hydrogen terminal diamond field effect transistor containing carbon-germanium bond and carbon-hydrogen bond.

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