Self-supporting thin film field effect transistor device based on beta-Ga2O3 and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor materials, and provides a beta-Ga2O3 self-supporting thin film field effect transistor device and a preparation method thereof, and the preparation method comprises preparation of a substrate deposited and grown by a beta-Ga2O3 self-supporting thin film, a sacrificial layer, a dielectric layer, a selective etchant solution and the beta-Ga2O3 self-supporting thin film. The problems of insufficient mechanical flexibility and poor interface quality of the traditional beta-Ga2O3 in the process of preparing a field effect transistor device are solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor materials, in particular to a β-Ga2O3 self-supporting thin film field effect transistor device and a preparation method thereof. Background Art

[0002] With their excellent electronic and material properties, two-dimensional field-effect transistors (2D FETs) hold broad application prospects in a variety of fields, including high-performance electronics, flexible electronics, low-power applications, quantum devices, and optoelectronics. With continued advancements in material preparation techniques and device design, 2D FETs will play an increasingly important role in the future development of electronic technology.

[0003] Traditional high-quality, flexible crystalline β-Ga2O3, due to its lack of mechanical flexibility, can lead to slight stretching or stress during mechanical peeling, dry transfer, and other steps in the fabrication of field-effect transistors (FETs). This can cause cracks or breakage in the FETs, impacting device performance and applications under dynamic deformation conditions. Furthermore, the traditional β-Ga2O3 fabrication process is prone to interface quality issues, leading to defects and stress in the contact between the β-Ga2O3 and other semiconductor materials, which in turn can cause increased leakage current and reduced breakdown voltage in FETs. Summary of the Invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a β-Ga2O3 self-supporting thin film field effect transistor device and a preparation method thereof, so as to solve one of the problems of insufficient mechanical flexibility and poor interface quality in the process of preparing field effect transistor devices using traditional β-Ga2O3.

[0005] In one aspect, an embodiment of the present invention provides a method for preparing a β-Ga2O3 free-standing film, comprising:

[0006] S101: Thin film growth: a sacrificial layer and a dielectric layer are sequentially grown on a SrTiO3 substrate by PLD;

[0007] S102: Etching and picking up: A selective etching solution is prepared to directionally etch the sacrificial layer. After the dielectric layer is separated from the sacrificial layer, a Si / SiO2 substrate is used to pick up the dielectric layer.

[0008] S103: Cleaning and annealing: Clean and remove the residual selective etching solution, and then anneal the Si / SiO2 substrate with the dielectric layer to obtain a self-supporting film.

[0009] Furthermore, after annealing the self-supporting film, film transfer is performed to prepare for subsequent preparation.

[0010] Preferably, the film transfer comprises: pressing PDMS onto a Si / SiO2 substrate with a self-supporting film, holding for 5-10 seconds, and then quickly peeling off the PDMS to pick up and transfer the self-supporting film.

[0011] Furthermore, the sacrificial layer is LSMO; the SrTiO3 substrate is 111 type, strontium titanate; and the dielectric layer is β-Ga2O3 (-201) type.

[0012] Furthermore, the selective corrosion solution is a mixed solution of KI+HCl;

[0013] Preferably, the concentration of the KI solution is 1 mol / L, the HCl solution is prepared by adding 1 g of 37% HCl to 100 g of deionized water, and the volume ratio of the KI solution to the HCl solution is 1:1.

[0014] Furthermore, a PLD-grown sacrificial layer was grown on a SrTiO3 substrate using a KrF excimer laser as the laser source at a growth temperature of 750°C, a frequency of 4 Hz, and 13 Pa, and then cooled to room temperature at a cooling rate of 7°C / min;

[0015] The wavelength of the laser output from the laser source is 248 nm.

[0016] Furthermore, a PLD-grown dielectric layer was used with a KrF excimer laser as the laser source, and a β-Ga2O3 layer was grown on the LSMO sacrificial layer at a growth temperature of 750°C, a frequency of 4 Hz, and 7 Pa. The heterostructure was then cooled to room temperature at a cooling rate of 7°C / min.

[0017] The wavelength of the laser output from the laser source is 248 nm.

[0018] On the one hand, an embodiment of the present invention provides a β-Ga2O3 self-supporting film, which is prepared by the above method.

[0019] In one aspect, an embodiment of the present invention provides a method for preparing a β-Ga2O3 self-supporting thin film field effect transistor device, comprising the steps of:

[0020] S201: A β-Ga2O3 free-standing film on a PDMS substrate is treated by mechanical exfoliation to obtain a thin layer of MoS2;

[0021] S202: Using a dry transfer technique, thin layers of MoS2 and β-Ga2O3 free-standing films are sequentially stacked onto a Si / SiO2 substrate to obtain a MoS2 / β-Ga2O3 free-standing film heterostructure;

[0022] S203: PMMA photoresist is coated on the surface of the heterostructure and fine patterning is performed using electron beam lithography. After development and fixing steps, 5 nm of chromium and 50 nm of gold are evaporated using electron beam evaporation technology to form the required vertical structure field effect transistor device.

[0023] Wherein, the β-Ga2O3 self-supporting film is a β-Ga2O3 self-supporting film on a PDMS substrate prepared by the above method.

[0024] On the one hand, an embodiment of the present invention provides a β-Ga2O3 self-supporting thin film field effect transistor device, and the β-Ga2O3 self-supporting thin film field effect transistor device is prepared using the above method.

[0025] Furthermore, it includes a substrate, a semiconductor layer, a dielectric layer and an electrode stacked in sequence, wherein the substrate is a 280nm±50nm Si / SiO2 substrate oxidized by dry oxygen; the semiconductor layer is a thin layer of MoS2 with a thickness of 6nm-7nm; the dielectric layer is a β-Ga2O3 self-supporting film with a thickness of 100nm±5nm; and the electrode is composed of 5nm chromium and 50nm gold.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] The self-supporting β-Ga2O3 film provided by this invention offers excellent mechanical support and is suitable for a variety of device architectures. Its high hardness and excellent mechanical stability enable it to maintain integrity under stress and deformation, enabling the fabrication of highly reliable devices using simple mechanical exfoliation and transfer techniques. Field-effect transistors fabricated using this material, combined with MoS2, a material with high electron mobility and bandgap tunability, exhibit excellent performance, including high switching speeds and operating frequencies. This has led to widespread application of β-Ga2O3 in wearable devices and other fields.

[0028] The present invention uses a β-Ga2O3 self-supporting film with good mechanical support, which is suitable for a variety of device architectures. Its high hardness and good mechanical stability enable it to maintain integrity under stress and deformation conditions, making it suitable for use in high-reliability devices. The surface interface quality is also improved to a certain extent, and it has a low leakage current, thereby making the device have better energy consumption.

[0029] The present invention utilizes the characteristics of MoS2 in transition metal dichalcogenides (TMD) materials, such as high electron mobility, bandgap tunability, good interface compatibility, and the high bandgap width, large dielectric constant, and excellent thermal stability of β-Ga2O3 self-supporting films, so that the device can be as low as 10 at a bias voltage of 1V and a gate voltage of -4V to 4V. -13A leakage current, and can provide a higher on-state current, achieving 10 5 On / Off ratio, with 125mV dec -1 The low subthreshold swing enables low power operation of the device.

[0030] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0032] Figure 1 A schematic diagram of a β-Ga2O3 self-supporting film preparation process provided by the present invention;

[0033] Figure 2 A physical picture of a β-Ga2O3 self-supporting film provided by the present invention;

[0034] Figure 3 A photodisplay image of a Si / SiO2 substrate and PDMS of a β-Ga2O3 self-supporting film provided by the present invention;

[0035] Figure 4 A diagram of a β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention;

[0036] Figure 5 A schematic structural diagram of a β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention;

[0037] Figure 6 This is the gate voltage regulation IV diagram of the β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention;

[0038] Figure 7 The transfer curve and leakage current of the β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention;

[0039] Figure 8 This is a schematic diagram of the preparation process of a β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0041] Current traditional preparation technologies, such as magnetron sputtering and pulsed laser deposition, expose many problems that are difficult to ignore when growing β-Ga2O3. On the one hand, the mechanical flexibility of the grown β-Ga2O3 is seriously insufficient, which makes it difficult to separate it from the substrate to form an independent self-supporting film and the subsequent mechanical transfer process, greatly hindering the manufacturing process of related devices. On the other hand, interface quality problems occur frequently, and there are many defects in the interface between β-Ga2O3 and the substrate, which not only affects the performance of the film, but also has a negative impact on the overall performance of the field-effect transistor based on β-Ga2O3, resulting in increased leakage current, reduced breakdown voltage and other problems, which limit the performance of the device in practical applications.

[0042] Furthermore, when characterizing the performance of field-effect transistor devices, the subthreshold swing is crucial. The subthreshold swing reflects the speed at which the device switches from the off state (off-state leakage current) to the on state (on-state current) in the subthreshold region. A smaller subthreshold swing means the device can switch states faster, thereby increasing switching speed. Furthermore, the subthreshold swing directly affects the energy efficiency of the field-effect transistor. A lower subthreshold swing allows the transistor to achieve significant current changes at lower gate voltages, thereby reducing power consumption. When operating at low voltages, the lower the subthreshold swing of the field-effect transistor, the better the switching characteristics that the device can maintain in the subthreshold region. This is critical for the design of ultra-low-power digital and analog circuits because it affects the performance and reliability of the circuits at extremely low operating voltages. However, traditional β-Ga2O3 preparation technology has difficulty achieving low subthreshold swings and cannot meet the current demand for high-performance, low-power devices.

[0043] To solve the above problems, the present invention provides a method for preparing a β-Ga2O3 self-supporting film, comprising the steps of:

[0044] S101: Thin film growth: Pulsed laser deposition (PLD) is used to sequentially deposit a sacrificial layer and a dielectric layer on a SrTiO3 substrate.

[0045] S102: Etching and picking up: A selective etching solution is prepared to directionally etch the sacrificial layer. After the dielectric layer is separated from the sacrificial layer, a Si / SiO2 substrate is used to pick up the dielectric layer.

[0046] S103: Cleaning and annealing: Clean and remove the residual selective etching solution, and then anneal the Si / SiO2 substrate with the dielectric layer to obtain a self-supporting film.

[0047] Furthermore, after annealing the self-supporting film, film transfer is performed to prepare for subsequent preparation. The film transfer includes: using polydimethylsiloxane (PDMS) to press on the Si / SiO2 substrate with the β-Ga2O3 self-supporting film, holding it for 5-10 seconds, and then quickly peeling off the PDMS to pick up and transfer the β-Ga2O3 self-supporting film.

[0048] Among them, the sacrificial layer is lanthanum strontium manganese oxide (LSMO); the SrTiO3 substrate is 111 type, strontium titanate, abbreviated as STO; the dielectric layer is β-Ga2O3 (-201) type.

[0049] The selective etching solution is a mixture of KI and HCl. The sacrificial LSMO layer is reduced from a +4 (+3) valence state of the Mn ions in the LSMO to a +2 valence state in the KI+HCl selective etching solution. This allows the LSMO layer to dissolve rapidly, resulting in a high-quality, independent β-Ga2O3(-2O1) thin film with excellent mechanical stability.

[0050] The concentration of the KI solution is 1 mol / L, the HCl solution is prepared by adding 1 g of 37% HCl to 100 g of deionized water, and the volume ratio of the KI solution to the HCl solution is 1:1.

[0051] Among them, the tiny lattice mismatch of the substrate SrTiO3 (111) plays a key role in the growth of LSMO on it. Its tiny lattice mismatch will generate a certain amount of stress between the film and the substrate, and this stress can regulate the strain state of the film. Through strain regulation, the lattice distortion during the film growth process can be reduced, thereby promoting the uniform growth of the film. In addition, the small lattice mismatch means that the lattice constants of the substrate and the film material are very close, which can effectively promote epitaxial growth. This situation helps the film material replicate the lattice structure of the substrate at the atomic level, forming a high-quality, single-crystalline film and improving the structural stability of the LSMO layer.

[0052] Specifically, the lattice constant of SrTiO3(111) is approximately (along the (111) plane), LSMO (such as La 0.7 Sr 0.3 The lattice constant of MnO3 is approximately (The difference with SrTiO3 is about 0.6%). This tiny lattice mismatch (~0.6%) will generate compressive stress at the interface during epitaxial growth of the film (the LSMO lattice is smaller than SrTiO3, and the film is compressed). When the lattice mismatch is small (<1%), the film adapts to the substrate lattice through elastic deformation rather than releasing stress through defects such as dislocations. This elastic strain can be evenly distributed in the film. The LSMO lattice is slightly distorted under compressive stress, which may change its electronic structure (such as Mn-O bond length and bond angle), thereby affecting the magnetic and electrical transport properties. In addition, compressive strain can enhance the ferromagnetic order of LSMO or regulate the magnetoresistance effect. Therefore, a small mismatch (~0.6%) can not only introduce sufficient strain to regulate the film properties, but also avoid film rupture or a surge in defect density due to excessive mismatch, forming a high-quality single crystal film.

[0053] Among them, the PLD growth sacrificial layer uses a KrF excimer laser as the laser source, and grows the LSMO sacrificial layer on the SrTiO3 substrate at a growth temperature of 750°C, a frequency of 4HZ, and 13Pa, and cools it to room temperature at a cooling rate of 7°C / min;

[0054] The wavelength of the laser output from the laser source is 248 nm.

[0055] The PLD-grown dielectric layer used a KrF excimer laser as the laser source, and a β-Ga2O3 layer was grown on the LSMO sacrificial layer at a growth temperature of 750°C, a frequency of 4 Hz, and 7 Pa. The heterostructure was then cooled to room temperature at a cooling rate of 7°C / min.

[0056] The wavelength of the laser output from the laser source is 248 nm.

[0057] Among them, PLD has the advantages of multi-material adaptability, high growth rate, strong controllability and suitability for growing heterostructures and multilayer films, which is conducive to the growth of the lanthanum strontium manganese oxide layer and β-Ga2O3 thin film layer heterostructure of the present invention.

[0058] On the one hand, the present invention also provides a β-Ga2O3 self-supporting film obtained by the above preparation method.

[0059] In one aspect, the present invention further provides a method for preparing a β-Ga2O3 self-supporting thin film field effect transistor device, comprising the steps of:

[0060] S201: using a mechanical exfoliation method to treat the β-Ga2O3 free-standing film on the PDMS substrate obtained above to obtain a thin layer of MoS2;

[0061] S202: Using a dry transfer technique, thin layers of MoS2 and β-Ga2O3 free-standing films are sequentially stacked onto a Si / SiO2 substrate to obtain a MoS2 / β-Ga2O3 free-standing film heterostructure;

[0062] S203: PMMA photoresist is coated on the surface of the heterostructure, and fine patterning is performed using electron beam lithography technology. After development and fixing steps, 5 nm of chromium and 50 nm of gold are evaporated using electron beam evaporation technology to form the required vertical structure field effect transistor device.

[0063] Among them, when transferring β-Ga2O3 self-supporting films in the preparation of field-effect transistors by dry transfer, a three-axis transfer platform is used for transfer and it needs to be heated to 80-90°C and wait for 20 minutes before slowly lifting it up.

[0064] On the one hand, the present invention also provides a β-Ga2O3 self-supporting thin film field effect transistor device, comprising a substrate, a semiconductor layer, a dielectric layer and an electrode stacked in sequence, wherein the substrate is a 280nm±50nm Si / SiO2 substrate oxidized by dry oxygen; the semiconductor layer is a thin layer of MoS2 with a thickness of 6nm-7nm; the dielectric layer is a β-Ga2O3 self-supporting thin film with a thickness of 100nm±5nm; and the electrode is composed of 5nm chromium and 50nm gold.

[0065] The electrodes were prepared using an eLINE Plus electron beam exposure system, with exposure parameters set to 160 μC / cm2 exposure dose, 0.72 nA beam current, and a 1000 μm × 1000 μm square area. The developer used was a 1:3 mixture of deionized water and isopropyl alcohol, with a development time of 20 seconds. Immediately after development, the silicon wafer was quickly placed in an isopropyl alcohol solution for a 25-second fixer.

[0066] Compared with the existing technology, the β-Ga2O3 self-supporting film provided by the present invention has good mechanical support and is suitable for a variety of device architectures. Its high hardness and good mechanical stability enable it to maintain integrity under stress and deformation conditions, so simple mechanical peeling and transfer technology can be used to prepare high-reliability devices. The field-effect transistor device made of MoS2 material with high electron mobility and band gap adjustability has excellent performance such as high switching speed and operating frequency, which promotes the widespread application of β-Ga2O3 in wearable and other fields.

[0067] The present invention uses a β-Ga2O3 self-supporting film with good mechanical support, which is suitable for a variety of device architectures. Its high hardness and good mechanical stability enable it to maintain integrity under stress and deformation conditions, making it suitable for use in high-reliability devices. The surface interface quality is also improved to a certain extent, and it has a low leakage current, thereby making the device have better energy consumption.

[0068] The present invention utilizes the characteristics of MoS2 in transition metal dichalcogenides (TMD) materials, such as high electron mobility, bandgap tunability, good interface compatibility, and the high bandgap width, large dielectric constant, and excellent thermal stability of β-Ga2O3 self-supporting films, so that the device can be as low as 10 at a bias voltage of 1V and a gate voltage of -4V to 4V. -13 A leakage current, and can provide a higher on-state current, achieving 10 5 On / Off ratio, with 125mV dec -1 The low subthreshold swing enables low power operation of the device.

[0069] The β-Ga2O3 self-supporting film of the present invention provides field-effect transistors with better device performance and reliability due to its advantages such as high dielectric properties, mechanical strength and thermal stability, and is particularly suitable for high-power, high-frequency and low-power electronic devices.

[0070] The selective etching solution used in the present invention is a mixed acidic solution of KI (1 mol / L) + HCl (1:1 volume ratio). This solution is highly selective and can directionally etch the LSMO layer. The β-Ga2O3 self-supporting film remains stable in the solution for a long time, which provides reliable protection for the subsequent preparation process.

[0071] Example 1

[0072] A method for preparing a β-Ga2O3 self-supporting film, comprising:

[0073] S101: A LSMO sacrificial layer was grown on a SrTiO3 substrate using pulsed laser deposition (PLD) technology using a KrF excimer laser (248 nm) as the laser source at a growth temperature of 750°C, a frequency of 4 Hz, and a pressure of 13 Pa. A β-Ga2O3 layer was then grown on the LSMO sacrificial layer at a growth temperature of 750°C, a frequency of 4 Hz, and a pressure of 7 Pa. The layer was then cooled to room temperature at a cooling rate of 7°C / min to prepare a SrTiO3 / LSMO / β-Ga2O structure.

[0074] S102: A mixed acidic solution prepared by KI+HCl is used as a selective etching solution to directionally etch the LSMO layer. The β-Ga2O3 self-supporting film required by the present invention can remain stable for a long time in this solution. After etching the LSMO for 6 hours, the β-Ga2O3 self-supporting film is removed and separated from the substrate and floats on the surface of the selective etching solution. The β-Ga2O3 self-supporting film is picked up using a Si / SiO2 substrate with a SiO2 thickness of 280nm±50nm and oxidized with dry oxygen;

[0075] The concentration of the KI solution is 1 mol / L, the HCl solution is prepared by adding 1 g of 37% HCl to 100 g of deionized water, and the volume ratio of the KI solution to the HCl solution is 1:1.

[0076] S103: removing the selective etching solution and residual KI crystals with a washing solution prepared by isopropyl alcohol, and then annealing the Si / SiO2 substrate with the β-Ga2O3 free-standing film at a treatment temperature of 180°C, a heating rate of 5°C / min, a holding time of 120 minutes, a cooling rate of 5°C / min, and an argon atmosphere, thereby obtaining an independent β-Ga2O3 free-standing film that can be mechanically transferred and dry-transferred;

[0077] S104: Press dimethylsiloxane (PDMS) onto a Si / SiO2 substrate with an independent β-Ga2O3 self-supporting film, hold for 5-10 seconds, and then quickly peel off the PDMS to easily pick up and transfer the β-Ga2O3 self-supporting film for device preparation.

[0078] Specifically, PDMS is pressed onto a Si / SiO2 substrate with a β-Ga2O3 free-standing film attached. After holding for 5-10 seconds, the tape is completely adhered to the PDMS surface. The entire system is placed in a vacuum chamber and maintained at a pressure of -0.1 Pa for 60-90 degrees. After the β-Ga2O3 free-standing film on the substrate is tightly adhered to the PDMS, it is quickly peeled off and picked up to transfer the β-Ga2O3 free-standing film.

[0079] Example 2: A β-Ga2O3 self-supporting film obtained by the preparation method of Example 1.

[0080] like Figure 2 As shown, this is a physical picture of a β-Ga2O3 self-supporting film provided by an embodiment of the present invention, that is, a physical picture after depositing an LSMO sacrificial layer and a β-Ga2O3 layer on a SrTiO3 substrate by pulsed laser deposition technology. The growth of the film can be intuitively observed from the figure.

[0081] like Figure 3As shown, it is a photoimage of a Si / SiO2 substrate and PDMS of a β-Ga2O3 self-supporting film field provided by the present invention. Among them, the sample in the left image is a photoimage of a β-Ga2O3 self-supporting film picked up and annealed on a Si / SiO2 substrate, and the right image is a photoimage of a β-Ga2O3 self-supporting film on a PDMS substrate by using simple mechanical peeling. Compared with traditional pulsed laser deposition technology or films deposited by magnetron sputtering, the β-Ga2O3 self-supporting film prepared by the present invention has good mechanical support, and can be used for convenient and less polluting dry transfer for β-Ga2O3 self-supporting film material transfer and device preparation.

[0082] Among them, the substrate provides controllable strain, few lattice defects and other characteristics, thereby improving the structural stability of the sacrificial layer; the sacrificial layer provides high conductivity, chemical stability, easy removal, thermal stability, etc., making it important for the growth of multilayer thin films; the dielectric layer provides better device performance and reliability due to its high dielectric properties, mechanical strength, thermal stability, etc., and is particularly suitable for high-power, high-frequency and low-power electronic devices. The dielectric layer is a β-Ga2O3(-201) type self-supporting film.

[0083] Example 3

[0084] A method for preparing a β-Ga2O3 self-supporting thin film field effect transistor device, comprising:

[0085] S201: using a mechanical exfoliation method to process the β-Ga2O3 free-standing film on the PDMS substrate obtained in Example 2 to obtain a thin layer of MoS2;

[0086] S202: Using a dry transfer technique, thin layers of MoS2 and β-Ga2O3 free-standing films are sequentially stacked onto a Si / SiO2 substrate to obtain a MoS2 / β-Ga2O3 free-standing film heterostructure;

[0087] Among them, when transferring β-Ga2O3 self-supporting films in the preparation of field-effect transistors by dry transfer, a three-axis transfer platform is used for transfer and it needs to be heated to 80-90°C and wait for 20 minutes before slowly lifting it up.

[0088] S203: PMMA photoresist is coated on the surface of the heterostructure, and fine patterning is performed using electron beam lithography technology. After development and fixing steps, the sample is subjected to electron beam evaporation to evaporate 5nm of chromium and 50nm of gold to form the required vertical structure field effect transistor device.

[0089] Example 4: A β-Ga2O3 self-supporting thin film field effect transistor device is obtained by the preparation method of Example 3, comprising a substrate, a semiconductor layer, a dielectric layer and an electrode stacked in sequence, wherein the substrate is a 280nm±50nm Si / SiO2 substrate oxidized by dry oxygen; the semiconductor layer is a thin layer of MoS2 with a thickness of 6nm-7nm; the dielectric layer is a β-Ga2O3 self-supporting thin film with a thickness of 100nm±5nm; and the electrode is composed of 5nm chromium and 50nm gold.

[0090] The electrodes were prepared using an eLINE Plus electron beam exposure system, with exposure parameters set to 160 μC / cm2 exposure dose, 0.72 nA beam current, and a 1000 μm × 1000 μm square area. The developer used was a 1:3 mixture of deionized water and isopropyl alcohol, with a development time of 20 seconds. Immediately after development, the silicon wafer was quickly placed in an isopropyl alcohol solution for a 25-second fixer.

[0091] On the basis of Examples 1 and 2, Figure 4 、 5 As shown, there are respectively a diagram of the β-Ga2O3 self-supporting thin film field effect transistor device provided by an embodiment of the present invention and a structural schematic diagram of the β-Ga2O3 self-supporting thin film field effect transistor device provided by an embodiment of the present invention. The composition and structure of the device can be clearly understood from the diagram.

[0092] Example 5: Electrical performance test of β-Ga2O3 self-supporting thin film field effect transistor device.

[0093] In the test, the electrodes at both ends of the thin layer of MoS2 were connected to the source and drain, and the electrodes on the β-Ga2O3 free-standing film were connected to the gate.

[0094] like Figure 6 As shown, it is a gate voltage regulation IV diagram of the β-Ga2O3 self-supporting thin film field effect transistor device provided by an embodiment of the present invention. This device utilizes the characteristics of high electron mobility of MoS2 and large dielectric constant of β-Ga2O3 self-supporting film, and successfully achieves good on-state current at a small bias voltage of -0.1V to 0.1V, and has obvious modulation phenomenon under the action of the gate voltage of the β-Ga2O3 self-supporting film.

[0095] like Figure 7 As shown in FIG, the transfer curve and leakage current diagram of the β-Ga2O3 self-supporting thin film field effect transistor device provided by the present invention are shown. Figure 7 As can be seen from the figure, the MoS2 transistor exhibits typical n-type characteristics, with a threshold voltage (Vth) estimated to be -2.6V; within the gate voltage range of ±4V, the transistor achieves 105 On / off ratio and 125mV dec -1 The β-Ga2O3 self-supporting thin film field effect transistor device of the present invention has certain competitiveness among two-dimensional material transistors. Because the top gate β-Ga2O3 has a high dielectric constant and excellent thermal stability, the device has a low subthreshold swing and low operating voltage, which is expected to be realized in practical low-power applications in the future. In addition, the top gate leakage current (I GS )1V bias, the device is as low as 10 at -4V to 4V gate voltage. -13 A, indicating the great potential of β-Ga2O3 free-standing films as high dielectric constant dielectrics in the field of electronic devices.

[0096] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a β-Ga2O3 self-supporting film, characterized in that: Including steps: S101: Thin film growth: a sacrificial layer and a dielectric layer are sequentially grown on a SrTiO3 substrate by PLD; S102: Etching and picking up: A selective etching solution is prepared to directionally etch the sacrificial layer. After the dielectric layer is separated from the sacrificial layer, a Si / SiO2 substrate is used to pick up the dielectric layer. S103: Cleaning and annealing: Clean and remove the residual selective etching solution, and then anneal the Si / SiO2 substrate with the dielectric layer to obtain a self-supporting film.

2. The method according to claim 1, wherein: After annealing the self-supporting film, film transfer is performed to prepare for subsequent preparation; Preferably, the film transfer comprises: pressing PDMS onto a Si / SiO2 substrate with a self-supporting film, holding for 5-10 seconds, and then quickly peeling off the PDMS to pick up and transfer the self-supporting film.

3. The method according to claim 1 or 2, characterized in that: The sacrificial layer is LSMO; the SrTiO3 substrate is 111 type, strontium titanate; and the dielectric layer is β-Ga2O3 (-201) type.

4. The method according to any one of claims 1 to 3, characterized in that: The selective corrosion solution is a mixed solution of KI+HCl; Preferably, the concentration of the KI solution is 1 mol / L, the HCl solution is prepared by adding 1 g of 37% HCl to 100 g of deionized water, and the volume ratio of the KI solution to the HCl solution is 1:

1.

5. The method according to any one of claims 1 to 4, characterized in that: The PLD growth sacrificial layer uses a KrF excimer laser as the laser source to grow the LSMO sacrificial layer on a SrTiO3 substrate at a growth temperature of 750°C, a frequency of 4 Hz, and 13 Pa, and is cooled to room temperature at a cooling rate of 7°C / min; The wavelength of the laser output from the laser source is 248 nm.

6. The method according to any one of claims 1 to 5, characterized in that: The PLD-grown dielectric layer uses a KrF excimer laser as the laser source. A β-Ga2O3 layer is grown on the LSMO sacrificial layer at a growth temperature of 750°C, a frequency of 4 Hz, and 7 Pa. The heterostructure is cooled to room temperature at a cooling rate of 7°C / min. The wavelength of the laser output from the laser source is 248 nm.

7. A β-Ga2O3 self-supporting film, characterized in that: The β-Ga2O3 self-supporting film is prepared by the method described in any one of claims 1-6.

8. A method for preparing a β-Ga2O3 self-supporting thin film field effect transistor device, characterized in that: Including steps: S201: A β-Ga2O3 free-standing film on a PDMS substrate is treated by mechanical exfoliation to obtain a thin layer of MoS2; S202: Using a dry transfer technique, thin layers of MoS2 and β-Ga2O3 free-standing films are sequentially stacked onto a Si / SiO2 substrate to obtain a MoS2 / β-Ga2O3 free-standing film heterostructure; S203: PMMA photoresist is coated on the surface of the heterostructure and fine patterning is performed using electron beam lithography. After development and fixing steps, 5 nm of chromium and 50 nm of gold are evaporated using electron beam evaporation technology to form the required vertical structure field effect transistor device. Wherein, the β-Ga2O3 self-supporting film is prepared by the method according to any one of claims 1 to 6 or the β-Ga2O3 self-supporting film on the PDMS substrate according to claim 7.

9. A β-Ga2O3 self-supporting thin film field effect transistor device, characterized in that: The β-Ga2O3 self-supporting thin film field effect transistor device is prepared by the method according to claim 8.

10. The β-Ga2O3 free-standing thin film field effect transistor device according to claim 9, characterized in that: It includes a substrate, a semiconductor layer, a dielectric layer and an electrode stacked in sequence, wherein the substrate is a 280nm±50nm Si / SiO2 substrate oxidized by dry oxygen; the semiconductor layer is a thin layer of MoS2 with a thickness of 6nm-7nm; the dielectric layer is a β-Ga2O3 self-supporting film with a thickness of 100nm±5nm; and the electrode is composed of 5nm chromium and 50nm gold.

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