Organic-inorganic Van der Waals heterojunction field effect transistor and preparation method thereof

Abstract

The invention discloses an organic-inorganic Van der Waals heterojunction field effect transistor and a preparation method thereof.The organic-inorganic Van der Waals heterojunction field effect transistor comprises a substrate, a dielectric layer, an active layer, a source electrode and a drain electrode, and the substrate, the dielectric layer and the active layer are arranged in parallel and connected in the vertical direction from bottom to top; the source electrode and the drain electrode are arranged in parallel and are connected to the upper surface of the active layer, the active layer is a two-dimensional ultrathin Van der Waals heterojunction, and the two-dimensional ultrathin Van der Waals heterojunction comprises an n-type semiconductor two-dimensional single crystal layer and a p-type semiconductor two-dimensional single crystal layer placed on the n-type semiconductor two-dimensional single crystal layer. According to the organic-inorganic Van der Waals heterojunction field effect transistor, the electron mobility is up to 118.42 cm < 2 > V <-1 > s <-1 >, the hole mobility is 2.3 cm < 2 > V <-1 > s <-1 >, and the switch ratio is up to 107. In the aspect of photoelectric detection performance, the responsivity reaches 68312.78 A / W, the response speed is 33 / 27ms, and the specific detection rate reaches 1.05 * 10 < 14 > Jones.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic-inorganic heterojunction preparation, and particularly relates to an organic-inorganic van der Waals heterojunction field effect transistor and a preparation method thereof. BACKGROUND

[0002] At present, polycrystalline thin films are concerned due to the advantage of large-area preparation. However, due to the problems of high defect state density, rough heterojunction interface and difficulty in complete depletion, the carrier mobility is low, the grating effect and the electric grating effect are limited, and the dark current is high. In contrast, the perfection of single crystal structure makes it exhibit low defect density and recombination loss in long-term operation, and has strong commercialization potential, which is suitable for high-performance photodetectors and other flexible and integrated applications. In particular, organic semiconductor single crystals are composed of single or several molecular layers of organic molecules combined by weak interaction, which has long-range order, no grain boundary and low defect density, which helps to build high-quality heterojunction interfaces. Especially, the organic-inorganic single crystal heterojunction, with its excellent electronic and photoelectric properties, can realize efficient light absorption, carrier separation and transport.

[0003] At present, inorganic semiconductor materials such as sulfides (such as GeS and MoS2) and selenides (such as InSe) have been widely used in combination with organic semiconductor materials to form organic-inorganic heterojunctions, thereby realizing the preparation of bipolar organic-inorganic heterojunction transistors. However, these organic-inorganic heterojunctions have deficiencies in morphology and interface quality, and generally face problems such as too large heterojunction thickness, poor interface quality and uncontrollable thickness, which leads to poor carrier transport performance of the transistor and low stability and on-off ratio, limiting the further improvement of its electrical performance. Zatko et al. prepared a WS2 / WSe2 / WS2 two-dimensional van der Waals heterojunction by pulsed laser deposition (PLD) method, which showed large-area uniform growth of materials and clear heterostructure-related transport characteristics, but the heterojunction still had problems of large thickness and poor interface quality. Therefore, how to successfully prepare a two-dimensional ultrathin organic-inorganic single crystal van der Waals heterojunction with small thickness, excellent interface quality, high mobility and high on-off ratio has become a key problem to be solved in the field of high-performance low-power logic circuits and high-performance photodetectors. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide an organic-inorganic van der Waals heterojunction field effect transistor, which has excellent carrier transport performance, high stability and good flexibility compatibility, and lays a solid foundation for the preparation of large-scale industrialized field effect transistor type detectors.

[0005] Another object of the present application is to provide a preparation method of an organic-inorganic van der Waals heterojunction field effect transistor, which prepares an n-type semiconductor two-dimensional monocrystalline layer (gamma-InSe monocrystal) by a mechanical exfoliation method, successfully transfers a p-type semiconductor two-dimensional monocrystalline layer (C6-DPA monocrystal) to the n-type semiconductor two-dimensional monocrystalline layer by van der Waals interaction, forms a van der Waals heterojunction, and realizes efficient light absorption, carrier separation and transmission by optimizing the thickness of the van der Waals heterojunction.

[0006] The object of the present application is achieved by the following technical solutions.

[0007] An organic-inorganic van der Waals heterojunction field effect transistor comprises a substrate, a dielectric layer, an active layer, a source electrode and a drain electrode, wherein the substrate, the dielectric layer and the active layer are arranged in parallel and connected in a vertical direction from bottom to top, and the source electrode and the drain electrode are arranged in parallel and connected to the upper surface of the active layer (the source electrode and the drain electrode are parallel to the active layer, respectively), wherein the active layer is a two-dimensional ultrathin van der Waals heterojunction, and the two-dimensional ultrathin van der Waals heterojunction is an n-type semiconductor two-dimensional monocrystalline layer and a p-type semiconductor two-dimensional monocrystalline layer placed thereon.

[0008] In the above technical solution, the thickness of the n-type semiconductor two-dimensional monocrystalline layer is 7-200 nm, the thickness of the p-type semiconductor two-dimensional monocrystalline layer is 5-20 nm, and the thickness of the active layer is 15-220 nm.

[0009] In the above technical solution, the n-type semiconductor two-dimensional monocrystalline layer is a gamma-InSe monocrystal, a GeS monocrystal or a MoS2 monocrystal, and the p-type semiconductor two-dimensional monocrystalline layer is a C6-DPA monocrystal.

[0010] In the above technical solution, the p-type semiconductor two-dimensional monocrystalline layer and the n-type semiconductor two-dimensional monocrystalline layer are combined to form a two-dimensional ultrathin van der Waals heterojunction through van der Waals interaction.

[0011] In the above technical solution, the substrate is a rigid substrate or a flexible substrate, the rigid substrate can be a silicon wafer or indium tin oxide (ITO), and the flexible substrate can be polyethylene naphthalate (PEN).

[0012] In the above technical solution, the dielectric layer is a first dielectric layer or a second dielectric layer, the first dielectric layer is a gate oxide layer (the first dielectric layer is a SiO2 layer), and the second dielectric layer is a first dielectric layer and an insulating layer arranged thereon (the second dielectric layer is a SiO2 layer and a hexagonal boron nitride layer arranged thereon), and the insulating layer is a hexagonal boron nitride (h-BN) layer.

[0013] In the technical scheme, when the dielectric layer is the first dielectric layer, the thickness of the active layer is 15-30 nm, the thickness of the n-type semiconductor two-dimensional monocrystal layer is 10-20 nm, and the thickness of the p-type semiconductor two-dimensional monocrystal layer is 5-10 nm.

[0014] In the technical scheme, when the dielectric layer is the second dielectric layer, the thickness of the active layer is 15-45 nm, the thickness of the n-type semiconductor two-dimensional monocrystal layer is 7-35 nm, and the thickness of the p-type semiconductor two-dimensional monocrystal layer is 5-10 nm.

[0015] In the technical scheme, the thickness of the dielectric layer is 100-400 nm.

[0016] In the technical scheme, the source electrode is one of gold electrode, aluminum electrode, copper electrode and silver electrode, the drain electrode is one of gold electrode, aluminum electrode, copper electrode and silver electrode, and the thickness of the source electrode and the drain electrode is 40-50 nm.

[0017] The preparation method of the organic-inorganic van der Waals heterojunction field effect transistor comprises the following steps:

[0018] Step 1: an n-type semiconductor two-dimensional monocrystal layer is arranged on a dielectric layer, and a p-type semiconductor two-dimensional monocrystal layer is arranged on the n-type semiconductor two-dimensional monocrystal layer, so as to obtain an active layer on the dielectric layer;

[0019] In the step 1, when the dielectric layer is the second dielectric layer, the insulating layer is prepared on the first dielectric layer by a mechanical exfoliation method, so as to obtain the second dielectric layer.

[0020] In the step 1, the substrate needs to be subjected to oxygen plasma treatment before use.

[0021] In the step 1, the n-type semiconductor two-dimensional monocrystal layer is prepared by the mechanical exfoliation method.

[0022] In the technical scheme, the mechanical exfoliation method comprises the following steps: the exfoliation material is adhered to a carrier film, the exfoliation material is subjected to N times of adhesive exfoliation operation, until the (remaining) exfoliation material on the carrier film is in a layered sheet, N=8-10; the layered sheet adhered to the carrier film is positioned on the first dielectric layer or the dielectric layer by dry transfer or wet transfer, the carrier film is exfoliated, cleaned and dried, and the layered sheet is obtained on the first dielectric layer or the dielectric layer, wherein the exfoliation material is an insulating material or an n-type semiconductor material, the insulating material is a hexagonal boron nitride (h-BN) crystal, and the n-type semiconductor material is a gamma-InSe crystal, a GeS crystal or a MoS2 crystal.

[0023] In the above technical solution, the method for peeling off the carrier film includes: heating the carrier film and the layered sheet at 50-95°C for 2-60 min, and cooling to room temperature, preferably heating at 80-95°C for 14-16 min.

[0024] In the above technical solution, the carrier film is blue adhesive tape.

[0025] In the above technical solution, when an insulating layer is prepared on the first dielectric layer by mechanical peeling, the peeling material is an insulating material; when an n-type semiconductor two-dimensional single crystal layer is prepared on the dielectric layer by mechanical peeling, the peeling material is an n-type semiconductor material.

[0026] In the above technical solution, the cleaning operation includes: soaking in acetone at 20-25°C for 1-5 minutes to remove residual adhesive.

[0027] In the above technical solution, the drying temperature is 20-25℃ room temperature, and the drying time is 10-14h.

[0028] In step 1, a two-dimensional single crystal layer of a p-type semiconductor is prepared by liquid phase epitaxy.

[0029] The method for preparing a two-dimensional single crystal layer of p-type semiconductor by liquid phase epitaxy includes: dissolving p-type semiconductor material in chlorobenzene to obtain a p-type semiconductor solution, adding 40-60 μL of the p-type semiconductor solution to the surface of water, and placing it at room temperature of 20-25°C until the chlorobenzene evaporates to obtain a two-dimensional single crystal layer of p-type semiconductor on the surface of water.

[0030] In the above technical solution, the p-type semiconductor material is 2,6-bis(4-hexylphenyl)anthracene (C6-DPA), and the structural formula of 2,6-bis(4-hexylphenyl)anthracene is as follows:

[0031] In the above technical solution, the concentration of p-type semiconductor material in the p-type semiconductor solution is 0.40 to 0.55 mg / mL.

[0032] Step 2: Set the source and drain on the surface of the active layer to obtain an organic-inorganic van der Waals heterojunction field-effect transistor.

[0033] In step 2, the source and drain electrodes are deposited on the surface of the active layer by vapor deposition.

[0034] In the above technical solution, the evaporation rate is The vacuum degree of vapor deposition is 1×10 -6 ~2×10 - 6 Pa.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. The organic-inorganic van der Waals heterojunction field-effect transistor obtained by this invention has high carrier mobility, large on / off ratio, and good stability, with an electron mobility as high as 118.42 cm⁻¹. 2 V -1 s -1 The hole mobility was 2.3 cm. 2 V -1 s -1 The on / off ratio reaches a maximum of 10. 7 The organic-inorganic van der Waals heterojunction field-effect transistor of the present invention has low interface defects, which ensures excellent environmental stability and interface quality. High crystallinity can effectively reduce carrier scattering, thereby achieving high electron and hole mobility, and thus giving it low power consumption and high on / off ratio.

[0037] 2. The present invention utilizes a simple device, an easy-to-operate mechanical exfoliation method, and the solution processability of organic semiconductors in the preparation method of two-dimensional ultrathin van der Waals heterojunctions. It is efficient and convenient, and the resulting organic-inorganic van der Waals heterojunction field-effect transistors have stable performance.

[0038] 3. The organic-inorganic van der Waals heterojunction field-effect transistor obtained in this invention possesses excellent photoelectric properties, enabling efficient separation and transport of photogenerated carriers, and significantly improving the response speed and sensitivity of photodetectors and transistors. Specifically, in terms of photoelectric detection performance, the responsivity reaches 68312.78 A / W, the response speed is 33 / 27 ms, and the specific detectivity is as high as 1.05 × 10⁻⁶. 14 Jones not only meets the needs of high-performance logic circuits, but also provides broad application prospects for the integration of photodetectors, flexible electronics, and novel low-dimensional devices. Attached Figure Description

[0039] Figure 1 A schematic diagram of the structure of an organic-inorganic van der Waals heterojunction field-effect transistor;

[0040] Figure 2 This is a schematic diagram of the process of placing an n-type semiconductor two-dimensional single crystal layer in Example 1;

[0041] Figure 3 This is a schematic diagram illustrating the process of preparing a two-dimensional single-crystal layer of a p-type semiconductor.

[0042] Figure 4 This is an optical microscope image of the γ-InSe single crystal in Example 1;

[0043] Figure 5 The images shown are (a) Raman spectroscopy and (b) X-ray spectroscopy of the γ-InSe single crystal in Example 1.

[0044] Figure 6(a) Optical microscope image and (b) AFM characterization diagram of the active layer in Example 1;

[0045] Figure 7 (a) XRD diffraction pattern and (b) Raman pattern of C6-DPA single crystal, γ-InSe single crystal and active layer of Example 1;

[0046] Figure 8 Optical microscopy characterization images of (a) the dielectric layer, (b) the γ-InSe single crystal on the dielectric layer, and (c) the active layer in Example 3;

[0047] Figure 9 The energy band diagrams of C6-DPA single crystal and γ-InSe single crystal in the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-9 are shown.

[0048] Figure 10 The images are optical microscope images, in which (a) is the two-dimensional single crystal layer of the n-type semiconductor in Example 10, (b) is the active layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 10, (c) is the two-dimensional single crystal layer of the n-type semiconductor in Example 11, and (d) is the active layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 11.

[0049] Figure 11 The transfer characteristic curves of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 are shown.

[0050] Figure 12 Comparison of electron mobility of organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-9;

[0051] Figure 13 The It curve is the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3;

[0052] Figure 14 The transfer characteristic curves of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 under gate voltage of -10 to 30V and source-drain bias of 1V are shown.

[0053] Figure 15 The organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 is shown in (a) the photoresponse curves under incident light of different wavelengths and (b) the responsivity (R) and specific detectivity (D*) under incident light of different wavelengths.

[0054] Figure 16 The organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 has (a) response time curves at different wavelengths and (b) response time at 365 nm.

[0055] Figure 17 (a) Optical microscope image of a flexible device, (b) Schematic diagram of bending it on a pen, (c) Schematic diagram of skin adhesion.

[0056] Wherein, 1: substrate, 2: dielectric layer, 3: active layer, 3-1: n-type semiconductor two-dimensional single crystal layer, 3-2: p-type semiconductor two-dimensional single crystal layer, 4: source, 5: drain. Detailed Implementation

[0057] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0058] γ-InSe single crystals were purchased from Shenzhen Six Carbon Technology Co., Ltd.

[0059] The hexagonal boron nitride (h-BN) crystals were purchased from Shenzhen Six Carbon Technology Co., Ltd.

[0060] 2,6-Bis(4-hexylphenyl)anthracene (C6-DPA) was purchased from Shanghai Daran Chemical Co., Ltd., with a purity ≥99.9%. The structural formula of C6-DPA is as follows:

[0061] Chlorobenzene (purity > 99%) was purchased from Sigma-Aldrich.

[0062] Acetone (purity: analytical grade) was purchased from Tianjin Yuanli Chemical Co., Ltd.

[0063] Isopropanol (purity: analytical grade) was purchased from Tianjin Kemei Chemical Reagent Co., Ltd.

[0064] The oxygen plasma cleaner was purchased from Zepto 116457 in Germany.

[0065] Example 1

[0066] like Figure 1 As shown, an organic-inorganic van der Waals heterojunction field-effect transistor includes: a substrate 1, a dielectric layer 2, an active layer 3, a source 4, and a drain 5. The substrate 1, dielectric layer 2, and active layer 3 are arranged in parallel and connected vertically from bottom to top (i.e., a layered structure). The source 4 and drain 5 are arranged in parallel and connected to the upper surface of the active layer 3. The active layer 3 is a two-dimensional ultrathin van der Waals heterojunction, which consists of an n-type semiconductor two-dimensional single crystal layer 3-1 and a p-type semiconductor two-dimensional single crystal layer 3-2 placed thereon. The n-type semiconductor two-dimensional single crystal layer 3-1 is a γ-InSe single crystal, and the p-type semiconductor two-dimensional single crystal layer 3-2 is a C6-DPA single crystal. The p-type semiconductor two-dimensional single crystal layer 3-2 and the n-type semiconductor two-dimensional single crystal layer 3-1 are bonded together through van der Waals interactions to form a two-dimensional ultrathin van der Waals heterojunction. The source 4 and drain 5 are each gold electrodes.

[0067] The fabrication method of the above-mentioned organic-inorganic van der Waals heterojunction field-effect transistor includes the following steps:

[0068] Step 1: The silicon wafer covered with the SiO2 layer (purchased from Suzhou Jingxi Electronics Technology Co., Ltd., the SiO2 layer is used as the dielectric layer, the thickness of the SiO2 layer is 300nm, the silicon wafer is used as substrate 1, the area of ​​the silicon wafer is 1.5cm×1.5cm, and the thickness of the silicon wafer is 1μm) is ultrasonicated with deionized water, acetone and isopropanol for 10 minutes each, then dried with a nitrogen gun, and the dielectric layer 2 is treated with oxygen plasma at 80W power for 10 minutes to obtain the substrate;

[0069] An n-type semiconductor two-dimensional single crystal layer 3-1 is prepared by mechanical exfoliation and placed on the dielectric layer 2 of the substrate. Then, a p-type semiconductor two-dimensional single crystal layer 3-2 is prepared by liquid phase epitaxy and placed on the n-type semiconductor two-dimensional single crystal layer 3-1, thus obtaining an active layer 3 on the dielectric layer 2.

[0070] A method for preparing a two-dimensional single crystal layer of n-type semiconductor (γ-InSe single crystal) includes: placing a bulk n-type semiconductor material (as a release material) on a blue adhesive tape (the blue adhesive tape as a carrier film), performing an adhesion and peeling operation on the n-type semiconductor material N times, where N=10, to reduce the overall thickness of the bulk n-type semiconductor material, thereby obtaining a layered thin sheet of n-type semiconductor two-dimensional single crystal layer on the blue adhesive tape, wherein the n-type semiconductor material is γ-InSe crystal.

[0071] like Figure 2 As shown, the method for placing the n-type semiconductor two-dimensional single crystal layer 3-1 includes: pressing the n-type semiconductor two-dimensional single crystal layer 3-1, which is attached to blue adhesive tape, onto the dielectric layer 2 of the substrate using a dry transfer method (adhesive bonding, gently pressing with a cotton swab to ensure no gaps); peeling off the blue adhesive tape; placing the substrate with the n-type semiconductor two-dimensional single crystal layer 3-1 (with the n-type semiconductor two-dimensional single crystal layer 3-1 facing down in contact with the heating stage) on an 80°C heating stage and heating continuously for 15 minutes to increase the interaction between the n-type semiconductor two-dimensional single crystal layer 3-1 and the dielectric layer 2; cooling to room temperature; and removing the blue adhesive tape. Cleaning: immersing in acetone at 20–25°C for 3 minutes to remove residual adhesive from the surface of the n-type semiconductor two-dimensional single crystal layer 3-1. Drying at room temperature (20–25°C) for 12 hours to obtain the n-type semiconductor two-dimensional single crystal layer 3-1 on the dielectric layer 2.

[0072] like Figure 3 As shown, the method for preparing a two-dimensional single crystal layer of p-type semiconductor 3-2 by liquid phase epitaxy includes: dissolving the p-type semiconductor material in chlorobenzene by ultrasonic oscillation for 2 hours to obtain a p-type semiconductor solution; and then preparing a solution with a volume of 76.9 cm³. 320 mL of purified water was poured into a petri dish, and 50 μL of p-type semiconductor solution was added to the surface of the purified water. The petri dish was sealed with plastic wrap to ensure good water oxygen saturation and placed in a dry and quiet environment at room temperature of 20-25°C for 12 hours until chlorobenzene evaporated. A two-dimensional single crystal layer 3-2 of p-type semiconductor was obtained on the surface of the purified water. The p-type semiconductor material was C6-DPA, and the concentration of p-type semiconductor material in the p-type semiconductor solution was 0.45 mg / mL.

[0073] The thickness of the p-type semiconductor two-dimensional single crystal layer 3-2 obtained on the surface of pure water is 5-30 nm, with an average thickness of 10 nm. A 5.2 nm thick p-type semiconductor two-dimensional single crystal layer 3-2 on the surface of pure water is selected for use in an organic-inorganic van der Waals heterojunction field-effect transistor. The method for placing the p-type semiconductor two-dimensional single crystal layer 3-2 includes: placing a substrate containing an n-type semiconductor two-dimensional single crystal layer 3-1 (with the n-type semiconductor two-dimensional single crystal layer 3-1 facing down) onto the p-type semiconductor two-dimensional single crystal layer 3-2 in pure water (the thickness of the p-type semiconductor two-dimensional single crystal layer 3-2 at this location is 5.2 nm), resulting in an area of ​​1500 μm. 2 The p-type semiconductor two-dimensional single crystal layer 3-2 is transferred to the surface of the n-type semiconductor two-dimensional single crystal layer 3-1 and dried at room temperature of 20-25°C to obtain the active layer 3 on the dielectric layer 2 of the substrate.

[0074] Step 2, with a vacuum degree of 1×10 -6 In the vacuum cavity of Pa, through The source and drain electrodes are deposited at a certain evaporation rate to form a source electrode 4 with a thickness of 50 nm and a drain electrode 5 with a thickness of 50 nm on the surface of the active layer, thereby obtaining an organic-inorganic van der Waals heterojunction field-effect transistor.

[0075] The area, thickness, p-type semiconductor two-dimensional single crystal layer thickness, and active layer thickness of the organic-inorganic van der Waals heterojunction field-effect transistor prepared in Example 1 are shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] Examples 2-9

[0080] A method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor includes the following steps:

[0081] Step 1: The silicon wafer covered with the SiO2 layer (purchased from Suzhou Jingxi Electronics Technology Co., Ltd., the thickness of the SiO2 layer is 300nm, the silicon wafer is used as substrate 1, the area of ​​the silicon wafer is 1.5cm×1.5cm, and the thickness of the silicon wafer is 1μm) is ultrasonically treated with deionized water, acetone and isopropanol for 10 minutes each, then dried with a nitrogen gun, and oxygen plasma treatment is performed on one side of the SiO2 layer for 10 minutes at 80W power.

[0082] Using hexagonal boron nitride (h-BN) crystal as the exfoliation material, a 10 nm thick hexagonal boron nitride layer (insulating layer) was prepared on the SiO2 layer by mechanical exfoliation. The SiO2 layer and the hexagonal boron nitride layer were used as the dielectric layer (BN / SiO2) to obtain a dielectric layer with a thickness of 310 nm. The mechanical peeling method includes: attaching block-shaped hexagonal boron nitride (h-BN) crystals to a blue adhesive tape, performing the adhesion and peeling operation on the hexagonal boron nitride (h-BN) crystals 10 times until the (remaining) hexagonal boron nitride (h-BN) crystals on the blue adhesive tape form layered flakes, and then positioning the layered flakes attached to the blue adhesive tape onto the SiO2 layer by dry transfer, heating at 65℃ for 15 minutes, cooling to room temperature, removing the blue adhesive tape, immersing the remaining part after removing the blue adhesive tape in acetone at 20-25℃ for 3 minutes to remove the residual adhesive on the surface of the layered flakes, and drying at room temperature at 20-25℃ for 12 hours to obtain a hexagonal boron nitride (h-BN) layer on the SiO2 layer.

[0083] An n-type semiconductor two-dimensional single crystal layer 3-1 is prepared by mechanical exfoliation and placed on a dielectric layer 2. Then, a p-type semiconductor two-dimensional single crystal layer 3-2 is prepared by liquid phase epitaxy and placed on the n-type semiconductor two-dimensional single crystal layer 3-1, thus obtaining an active layer 3 on the dielectric layer 2.

[0084] A method for preparing a two-dimensional single crystal layer of n-type semiconductor (γ-InSe single crystal) includes: placing a bulk n-type semiconductor material (as a release material) on a blue adhesive tape (the blue adhesive tape as a carrier film), performing an adhesion and peeling operation on the n-type semiconductor material N times, where N=10, to reduce the overall thickness of the bulk n-type semiconductor material, thereby obtaining a layered thin sheet of n-type semiconductor two-dimensional single crystal layer on the blue adhesive tape, wherein the n-type semiconductor material is γ-InSe crystal.

[0085] The method for placing an n-type semiconductor two-dimensional single crystal layer 3-1 includes: with the n-type semiconductor two-dimensional single crystal layer facing the PDMS film, attaching blue adhesive tape to the PDMS film, peeling off the blue adhesive tape to obtain the n-type semiconductor two-dimensional single crystal layer on the PDMS film; placing the PDMS film on a glass slide, transferring it to a microscope, using a two-dimensional transfer platform to connect the n-type semiconductor two-dimensional single crystal layer and the dielectric layer on the PDMS film, continuously heating at 80°C for 5 minutes (to remove the adhesiveness of the PDMS film), peeling off the PDMS film to obtain the n-type semiconductor two-dimensional single crystal layer on the dielectric layer. The area and thickness of the n-type semiconductor two-dimensional single crystal layer are shown in Table 2.

[0086] The method for preparing the p-type semiconductor two-dimensional single crystal layer 3-2 by liquid phase epitaxy is the same as in Example 1 (selecting p-type semiconductor two-dimensional single crystal layers 3-2 of different thicknesses). The method for placing the p-type semiconductor two-dimensional single crystal layer 3-2 is the same as in Example 1. The thickness of the p-type semiconductor two-dimensional single crystal layer and the thickness of the active layer are shown in Table 2.

[0087] Step 2 is the same as "Step 2" in Example 1.

[0088] Table 2

[0089]

[0090] Example 10

[0091] A method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor is basically the same as the method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor in Example 1, except that the two-dimensional single crystal layer of the n-type semiconductor is a GeS single crystal, and the corresponding n-type semiconductor material used is GeS crystal.

[0092] Example 11

[0093] A method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor is basically the same as the method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor in Example 1, except that the two-dimensional single crystal layer of the n-type semiconductor is MoS2 single crystal, and the corresponding n-type semiconductor material used is MoS2 crystal.

[0094] The width-to-length ratio of the channel of the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-11 is 1:3.

[0095] The two-dimensional single-crystal layer (γ-InSe single crystal) of the n-type semiconductor in Example 1 was subjected to optical microscopy, Raman spectroscopy, and X-ray spectroscopy. The optical microscopy methods included... Figure 4 As shown, Raman characterization ( Figure 5 a) and X-ray characterization ( Figure 5 b) such asFigure 5 As shown. By Figure 4 It can be seen that γ-InSe single crystals possess good single crystal thickness and area. From... Figure 5 From (a), we know that at 110cm -1 Raman Peak is A 1 1g At 180cm -1 The Raman peak is E 1 2g At 226cm -1 Raman Peak is A 2 1g This indicates that the γ-InSe single crystal is relatively thin, and proves that it is the γ phase; Figure 5 From (b), we can see that at an incident angle of 11... 0 ,twenty two 0 32 ° and 44 0 The diffraction peaks at the locations correspond to the (003), (006), (009), and (0012) crystal planes of the γ-configuration InSe crystal, respectively, indicating that the γ-InSe single crystal is a γ-configuration crystal and there are no diffraction peaks of other impurity components, indicating that the γ-InSe single crystal has high purity and good crystal quality.

[0096] Optical microscopy was performed on the active layer of Example 1. Figure 6 a) and AFM characterization ( Figure 6 test b), such as Figure 6 As shown, by Figure 6 As shown in (a), the two-dimensional ultrathin van der Waals heterostructure formed by C6-DPA single crystal and γ-InSe single crystal has clear interface boundaries, indicating high-quality heterostructure construction, and the surface is relatively smooth and flat with regular angular shapes; Figure 6 As shown in (b), the two-dimensional ultrathin van der Waals heterostructure has good uniformity and low roughness, with a mean square roughness (Rq) of 0.32 nm.

[0097] The C6-DPA single crystal, γ-InSe single crystal, and active layer of Example 1 were compared with those of Example 1. Figure 7 XRD diffraction and Raman characterization were performed on the "Heterojunction" (in the image). The XRD diffraction pattern is shown below. Figure 7 As shown in (a), the Raman characterization is as follows Figure 7 As shown in (b). By Figure 7 As shown in (a), the active layer exhibits no obvious peak shift, indicating good crystallization quality; Figure 7As shown in (b), there is only a change in Raman peak intensity among the C6-DPA single crystal, γ-InSe single crystal, and active layer, without significant peak shift. This indicates that the active layer forms a good heterostructure. This proves that the two-dimensional ultrathin van der Waals heterostructure was successfully prepared and has high quality.

[0098] Figure 8 The image shows the optical microscope characterization of Example 3, where (a) is the dielectric layer, (b) is the γ-InSe single crystal on the dielectric layer, and (c) is the active layer. Figure 8 It can be seen that the active layer in Example 3 has high crystal quality.

[0099] Figure 9 The energy band diagrams of C6-DPA single crystal and γ-InSe single crystal in the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-9 are shown below. Figure 9 It can be seen that the conduction band of γ-InSe single crystal is -4.4 eV, the valence band is -5.7 eV, and the band gap is 1.26 eV; the conduction band of C6-DPA single crystal is -2.84 eV, the valence band is -5.6 eV, and the band gap is 2.76 eV. This indicates that the two-dimensional ultrathin van der Waals heterojunction formed by the combination of C6-DPA single crystal and γ-InSe single crystal through van der Waals interaction is a type II heterojunction.

[0100] Figure 10 These are optical microscope images of the n-type semiconductor two-dimensional single crystal layer and the active layer of the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 10 and 11, wherein (a) is the n-type semiconductor two-dimensional single crystal layer of Example 10, (b) is the active layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 10, (c) is the n-type semiconductor two-dimensional single crystal layer of Example 11, and (d) is the active layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 11. Figure 10 It can be seen that the high-quality construction of the two-dimensional ultrathin van der Waals heterojunction (active layer) in Examples 10 and 11 proves that the preparation method of the present invention has universality.

[0101] Comparative Example 1

[0102] A field-effect transistor (FET) without a p-type semiconductor two-dimensional single crystal layer (organic layer) is disclosed. The fabrication method of the field-effect transistor in this comparative example is basically the same as that of the organic-inorganic van der Waals heterojunction FET obtained in Example 1, except for the fabrication method of the n-type semiconductor two-dimensional single crystal layer (γ-InSe single crystal), the method of placing the n-type semiconductor two-dimensional single crystal layer 3-1, and the fact that this comparative example does not require the placement of a p-type semiconductor two-dimensional single crystal layer. The fabrication method of the n-type semiconductor two-dimensional single crystal layer (γ-InSe single crystal) and the method of placing the n-type semiconductor two-dimensional single crystal layer 3-1 in Comparative Example 1 can be found in the literature: Chang et al. “Synthesis of Large-Area InSe Monolayersby Chemical Vapor Deposition” Small. 14 (2018), 1802351. https: / / doi.org / 10.1002 / smll.201802351, specifically the InSe layer growth and InSe transfer process.

[0103] Comparative Example 1: A monolayer InSe (γ-InSe single crystal) was synthesized on a mica substrate using chemical vapor deposition (CVD). Polymethyl methacrylate (PMMA) was uniformly coated onto the surface of the monolayer InSe using spin coating to form a PMMA support film. The sample was then immersed in distilled water to separate the InSe interface from the mica substrate using the wetting effect of the water. After interface separation, the support film and its loaded monolayer InSe were lifted and precisely transferred onto a SiO2 layer. The support film was then removed by dissolving it in acetone. The thickness of the n-type semiconductor two-dimensional single crystal layer of the free field-effect transistor obtained in this comparative example was 0.84 nm, and the area was 600 μm. 2 .

[0104] Example 12

[0105] Under dark conditions, the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-9 and the inorganic field-effect transistor obtained in Comparative Example 1 were subjected to electrical performance tests at a source-drain voltage of 2V and a gate voltage of -45V to 45V, and transfer characteristic curves were obtained. According to the mobility formula described in the literature Zhou et al. “Accurate Field-Effect Mobility and Threshold Voltage Estimation for Thin-Film Transistors with Gate-Voltage-Dependent Mobility in Linear Region.” Advanced Electronic Materials. 9(2022):2200786. https: / / doi.org / 10.1002 / aelm.202200786., electron mobility and hole mobility were calculated from the transfer characteristic curves, and the on / off ratio was obtained from the transfer characteristic curves. The electron mobility, hole mobility, and on / off ratio are shown in Table 3. The transfer characteristic curve of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 is shown in Table 3. Figure 11 As shown, the electron mobility of the organic-inorganic van der Waals heterojunction field-effect transistors obtained in Examples 1-9 is compared to that of... Figure 12 As shown.

[0106] Table 3

[0107]

[0108] As shown in Table 3, the on / off ratio performance of the organic-inorganic van der Waals heterojunction field-effect transistor improves with decreasing active layer thickness in the embodiments. Notably, electron mobility does not exhibit a negative correlation with thickness. The organic-inorganic van der Waals heterojunction field-effect transistor demonstrates the best mobility performance when the active layer thickness is 25 nm, with an electron mobility as high as 118.42 cm⁻¹. 2 V -1 s -1 The hole mobility is as high as 2.3cm. 2 V -1 s -1Compared to Comparative Example 1, the organic-inorganic van der Waals heterojunction field-effect transistor obtained by this invention has a simpler operation process and superior performance. Furthermore, by adding an insulating layer to the SiO2 layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 1, the mobility and on / off ratio of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 are significantly improved. This is attributed to the lower lattice defect and impurity concentration of the single-crystal heterojunction, resulting in lower carrier scattering and recombination probabilities; the insulating layer can shield interface impurity scattering and surface phonon scattering.

[0109] The electrical performance of currently reported organic-inorganic heterojunction transistors is shown in Table 4. Compared with currently reported organic-inorganic heterojunction transistors, the organic-inorganic van der Waals heterojunction field-effect transistor of this invention exhibits superior electrical performance in terms of on / off ratio and electron mobility, resulting in more outstanding overall performance.

[0110] Table 4

[0111]

[0112] References:

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[0118] [6].A J Molina-Mendoza,L Vaquero-Garzon,S Leret,et al.Engineering theoptoelectronic properties of MoS2 photodetectors through reversiblenoncovalent functionalization.Chem.Commun.,2016,52,14365.

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[0131] Example 13

[0132] The It curve of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3, under dark conditions and an atmospheric environment of 20-25°C, was obtained after a 3000-second electrical performance test (with the on-state voltage set at 30V and the off-state voltage at -10V). Figure 13 As shown. By Figure 13 It can be seen that the switching performance is still good within 3000 seconds, which proves that the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 has good cycle stability.

[0133] Example 14

[0134] The organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 was placed in an atmospheric environment at 20–25°C for 4 months, and its electrical performance under dark conditions was tested in month T (T = 0, 1, 2, and 4). The transfer characteristic curves of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 at gate voltages of -10–30V and source-drain bias voltages of 1V are shown below. Figure 14 As shown. By Figure 14 It can be seen that the transfer characteristic curve after 4 months of storage is similar to that at the 0th ( Figure 14 The transfer characteristic curves obtained in January and February for "Prinstine" showed almost no change, and its on / off ratio still reached 10. 6 This demonstrates that organic-inorganic van der Waals heterojunction field-effect transistors have good environmental stability.

[0135] Example 15

[0136] For photodetectors, the transport capability of photogenerated carriers is a powerful strategy for providing optical gain and maintaining high responsivity. This invention provides a method for fabricating high-quality organic-inorganic van der Waals heterojunctions (active layers), which not only achieves high mobility but also lays the foundation for fabricating high-performance photodetectors. The organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 is applied to the research of broadband detectors, providing new technical solutions for fields such as bioimaging, infrared remote sensing, artificial intelligence, and night vision. Thanks to the synergistic effect of the strong built-in electric field at the organic-inorganic heterojunction interface and the complementary light absorption characteristics between the heterojunction material layers, the organic-inorganic van der Waals heterojunction field-effect transistor achieves a broadband response in the visible-near-infrared band (365–980 nm). The high-quality crystalline heterojunction promotes electron-hole pair separation, further enhancing the optical response of the organic-inorganic van der Waals heterojunction field-effect transistor.

[0137] To verify whether the active layer of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 possesses good photoelectric detection capability across a broad spectral range from ultraviolet to visible to near-infrared, the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 was tested at room temperature under a constant optical power density (120 μW / cm²). 2 Irradiation with incident light of different wavelengths (365nm, 405nm, 520nm, 655nm, 808nm, and 980nm) and drain-source voltage V ds Light response characteristics under a voltage of 2V. For example... Figure 15 As shown, a) represents the light response curves under incident light of different wavelengths, and b) represents the responsivity (R) and specific detectivity (D*) calculated from the light response curves under incident light of different wavelengths. Figure 15As shown in a), the organic-inorganic van der Waals heterojunction field-effect transistor exhibits good switching characteristics under incident light of different wavelengths. Based on the formulas for responsivity (R) and specific detectivity (D*) in the literature Gao et al. “Enhancement of Electronic and Optoelectronic Performance of the InSeMultilayer by Surface Transfer Engineering” ACS Applied Electronic Materials. 4(2022):5867-5874. https: / / pubs.acs.org / doi / 10.1021 / acsaelm.2c01041, the responsivity R and specific detectivity D* of the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 were calculated, and curves were plotted, as shown below. Figure 15 As shown in b), the organic-inorganic van der Waals heterojunction field-effect transistor exhibits the highest photocurrent, responsivity, and specific detectivity under 405 nm illumination, with R and D* of 68312.78 A / W and 1.05 × 10⁻⁶, respectively. 14 Jones. Figure 15 In a), "dark" represents the organic-inorganic van der Waals heterojunction field-effect transistor obtained in test example 3 under dark conditions at room temperature and with drain-source voltage V ds The optical response curve under a voltage of 2V is used to calculate the responsivity R and specific detectivity D*.

[0138] Example 16

[0139] Response speed is one of the key indicators for evaluating the performance of photodetectors, directly affecting the application of organic-inorganic van der Waals heterojunction field-effect transistors (OFETs) in high-speed photoelectric signal detection and processing. OFETs with short response times can identify and track changes in optical signals more quickly, and can be used in high-speed communication, rapid imaging, dynamic sensing, and real-time detection systems.

[0140] The organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 was tested at room temperature under a constant optical power density (120 μW / cm²). 2 Irradiation with incident light of different wavelengths (365nm, 405nm, 520nm, 655nm, 808nm, and 980nm) and drain-source voltage V ds Response speed test was performed under 2V conditions, such as Figure 16 As shown in the figure. Figure a represents the time response curves of the organic-inorganic van der Waals heterojunction field-effect transistor at different wavelengths, and figure b represents the response time of the organic-inorganic van der Waals heterojunction field-effect transistor at 365 nm. Figure 16As can be seen from a, this organic-inorganic van der Waals heterojunction field-effect transistor can produce significant photocurrent responses to incident light of different wavelengths, including 365nm, 405nm, 520nm, 655nm, 808nm, and 980nm. Figure 16 As can be seen from b, organic-inorganic van der Waals heterojunction field-effect transistors exhibit excellent performance with rise times as short as 33ms and fall times as short as 27ms.

[0141] Table 5 shows the performance of reported organic-inorganic heterojunction transistors and the organic-inorganic van der Waals heterojunction field-effect transistor obtained in Example 3 in terms of responsivity, response speed, specific detectivity, and detection wavelength. As can be seen from Table 5, the organic-inorganic van der Waals heterojunction field-effect transistor obtained in this invention significantly outperforms most reported photodetectors with similar structures. This invention provides important technical support and theoretical basis for the development of high-performance broadband two-dimensional photodetectors.

[0142] Table 5

[0143]

[0144] References

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[0163] Example 17

[0164] To investigate the flexibility compatibility of the two-dimensional ultrathin van der Waals heterojunction (active layer), the two-dimensional ultrathin van der Waals heterojunction from Example 1 was placed on a flexible substrate (polyethylene naphthalate) according to the preparation method of Example 1 to obtain a flexible device. The flexible device was then placed on a pen for dynamic bending testing, such as... Figure 17 As shown in (b). A schematic diagram of skin adhesion for flexible devices is shown below. Figure 17 As shown in (c), the optical microscope of the flexible device is as follows Figure 17 As shown in (a), by Figure 17 It is known that when the substrate is flexible, the two-dimensional ultrathin van der Waals heterojunction (active layer) has excellent bending adaptability and can be applied to flexible displays and optoelectronic devices.

[0165] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. An organic-inorganic van der Waals heterojunction field-effect transistor, characterized in that, include: The system comprises a substrate, a dielectric layer, an active layer, a source electrode, and a drain electrode. The substrate, dielectric layer, and active layer are arranged in parallel and connected vertically from bottom to top. The source electrode and drain electrode are arranged in parallel and connected to the upper surface of the active layer. The active layer is a two-dimensional ultrathin van der Waals heterojunction, which is an n-type semiconductor two-dimensional single crystal layer and a p-type semiconductor two-dimensional single crystal layer placed thereon.

2. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 1, characterized in that, The n-type semiconductor two-dimensional single crystal layer is γ-InSe single crystal, GeS single crystal or MoS2 single crystal, and the p-type semiconductor two-dimensional single crystal layer is C6-DPA single crystal.

3. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 1, characterized in that, The dielectric layer is either a first dielectric layer or a second dielectric layer; the first dielectric layer is a gate oxide layer; the second dielectric layer is the first dielectric layer and an insulating layer disposed thereon, the insulating layer being a hexagonal boron nitride layer.

4. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 1, characterized in that, The thickness of the n-type semiconductor two-dimensional single crystal layer is 7–200 nm; the thickness of the p-type semiconductor two-dimensional single crystal layer is 5–20 nm; and the thickness of the active layer is 15–220 nm.

5. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 1, characterized in that, The p-type semiconductor two-dimensional single crystal layer and the n-type semiconductor two-dimensional single crystal layer are combined through van der Waals interactions to form a two-dimensional ultrathin van der Waals heterojunction.

6. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 3, characterized in that, When the dielectric layer is the first dielectric layer, the thickness of the active layer is 15-30 nm, the thickness of the n-type semiconductor two-dimensional single crystal layer is 10-20 nm, and the thickness of the p-type semiconductor two-dimensional single crystal layer is 5-10 nm. When the dielectric layer is the second dielectric layer, the thickness of the active layer is 15-45 nm, the thickness of the n-type semiconductor two-dimensional single crystal layer is 7-35 nm, and the thickness of the p-type semiconductor two-dimensional single crystal layer is 5-10 nm.

7. The organic-inorganic van der Waals heterojunction field-effect transistor according to claim 1, characterized in that, The thickness of the dielectric layer is 100–400 nm.

8. The method for fabricating an organic-inorganic van der Waals heterojunction field-effect transistor as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: An n-type semiconductor two-dimensional single crystal layer is formed on the dielectric layer, and then a p-type semiconductor two-dimensional single crystal layer is formed on the n-type semiconductor two-dimensional single crystal layer to obtain an active layer on the dielectric layer. Step 2: Set the source and drain on the surface of the active layer to obtain an organic-inorganic van der Waals heterojunction field-effect transistor.

9. The preparation method according to claim 8, characterized in that, In step 1, when the dielectric layer is the second dielectric layer, an insulating layer is prepared on the first dielectric layer by mechanical peeling to obtain the second dielectric layer; In step 1, an n-type semiconductor two-dimensional single crystal layer is prepared by mechanical exfoliation.

10. The preparation method according to claim 8, characterized in that, In step 1, a two-dimensional single crystal layer of a p-type semiconductor is prepared by liquid phase epitaxy.

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