Quasi-one-dimensional (TaSe4)2I and MoTe2 mixed-dimensional heterojunction phototransistor detector and preparation method

Abstract

A quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector and a preparation method thereof. The detector comprises, from bottom to top, a Si substrate, a SiO2 gate dielectric layer, a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 nanofilms. Metal electrodes are respectively provided on the quasi-one-dimensional (TaSe4)2I and MoTe2 nanofilms, forming a heterostructure of (TaSe4)2I, MoTe2, and metal electrodes. The preparation method comprises the following steps: (1) transferring a (TaSe4)2I nanowire onto a Si substrate; (2) transferring a MoTe2 nanofilm to one side of the (TaSe4)2I nanowire; (3) preparing a bottom electrode pattern; (4) performing positioning exposure and development on the bottom electrode pattern to expose the portion where the electrode needs to be evaporated; and (5) preparing a metal electrode. The present invention utilizes the composite effect of (TaSe4)2I / MoTe2 heterojunction to suppress dark current through a vertical structure; utilizes MoTe2 to increase light absorption, and simultaneously applies gate voltage to increase photocurrent, thereby obtaining high responsiveness and external quantum efficiency.

Description

Technical Field

[0001] The present invention relates to a phototransistor detector based on a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional composite structure, belonging to the technical field of low-dimensional materials and photoelectric functional devices. Technical Background

[0002] Polarization photodetectors, by recognizing light polarization, can achieve high resolution and more surface information for distant targets in complex environments. They are currently widely used in military and civilian fields such as bioimaging, optical radar, night vision, and remote sensing. In recent years, anisotropic low-dimensional materials have been widely used to fabricate polarization-sensitive photodetectors.

[0003] Quasi-one-dimensional materials, whose crystal structures contain one-dimensional atomic chains, exhibit large anisotropy in their optoelectronic properties due to their large intrinsic structural anisotropy, making them excellent candidates for polarization photodetection devices. Among them, the quasi-one-dimensional (TaSe4)2I is a Weyl semimetal material, belonging to the tetragonal crystal system and the I422 space group. [TaSe4] chains, serving as the basic structural framework, are arranged parallel to the c-axis and separated by iodine chains. Each [TaSe4] chain is composed of alternating Ta atoms and Se4 rectangles with four Se atoms at the corners. The low-symmetry crystal structure resulting from the [TaSe4] and II chains gives (TaSe4)2I remarkable anisotropic electrical, thermal, and optical properties. Furthermore, the unique topological semimetal band structure endows (TaSe4)2I with advantages such as high carrier mobility and ultra-broadband optical absorption. In summary, due to its unique structural anisotropy and excellent optoelectronic properties, the quasi-one-dimensional semimetal (TaSe4)2I has important application prospects in the field of polarization photodetection devices.

[0004] However, due to the band structure of the (TaSe4)2I semimetal, (TaSe4)2I-based photodetectors exhibit large dark currents, which severely impacts the device's signal-to-noise ratio. Therefore, a unique device structure design is urgently needed to address this issue, thereby improving the device's sensitivity, on / off ratio, and other comprehensive performance characteristics to meet practical application requirements.

[0005] Van der Waals heterostructures based on low-dimensional materials are currently emerging as promising candidates for next-generation electronic and optoelectronic devices due to their versatile device configurations and outstanding optoelectronic properties. Compared to traditional single-material devices, heterostructured devices can overcome the shortcomings of single materials and broaden the possibilities of functional nanoscale devices. Therefore, constructing heterojunction devices has the potential to overcome the large dark current limitation of quasi-one-dimensional (TaSe4)2I and realize high-performance polarization photodetectors. Summary of the Invention

[0006] The present invention addresses the shortcomings of photodetectors based on the quasi-one-dimensional semi-metallic material (TaSe4)2I in terms of detection performance, such as excessive dark current leading to a low signal-to-noise ratio. The present invention provides a phototransistor detector with a mixed dimensional heterostructure of quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2, which has excellent performance, can suppress the large dark current of (TaSe4)2I, and increase the photocurrent of the device. A method for preparing the phototransistor detector is also provided. The vertical structure of the heterojunction can accelerate carrier separation and suppress dark current; at the same time, MoTe2 increases the light absorption of the device, which will increase the photocurrent of the device. The photocurrent can be further increased by regulating the gate voltage. Therefore, the phototransistor detector based on the (TaSe4)2I / MoTe2 heterojunction has a high responsiveness and can achieve highly sensitive photodetection. Furthermore, due to the increase in carrier separation efficiency, the polarization detection capability of the device can also be enhanced.

[0007] The quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector of the present invention adopts the following technical solutions:

[0008] This composite phototransistor detector consists, from bottom to top, of a Si substrate, a SiO2 gate dielectric layer, a quasi-one-dimensional (TaSe4)2I2 nanofilm, and a two-dimensional MoTe2 nanofilm. Metal electrodes are placed on the quasi-one-dimensional (TaSe4)2I2 and MoTe2 nanofilms, forming a heterostructure of (TaSe4)2I2, MoTe22, and metal electrodes. The mixed-dimensional heterojunction (TaSe4)2I2 / MoTe2 serves as the channel material, with a Si substrate and SiO2 as the gate dielectric layer. Applying a gate voltage to the silicon modulates the photocurrent.

[0009] The thickness of the [TaSe4]2I nanowire is 50 to 200 nm.

[0010] The Si substrate is a heavily doped P-type silicon wafer with a surface SiO2 thickness of 280 to 300 nm.

[0011] The thickness of the MoTe2 nanofilm is 30-100 nm.

[0012] The metal electrodes are 3-5 nm chromium and 30-50 nm gold.

[0013] The detector described above combines (TaSe4)2I and MoTe2 via van der Waals forces to form a (TaSe4)2I / MoTe2 mixed-dimensional heterojunction. The vertical structure of this heterojunction improves carrier separation efficiency, suppressing the high dark current of the (TaSe4)2I. Furthermore, MoTe2 enhances the device's light absorption, increasing its photocurrent. The high photocurrent and low dark current give the one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor ultrasensitive photodetection performance. Furthermore, the large anisotropy and ultra-broadband response of the (TaSe4)2I heterojunction phototransistor endow it with polarization detection capabilities and visible-infrared broadband detection capabilities.

[0014] The method for preparing the quasi-one-dimensional [TaSe4]2I and two-dimensional MoTe2 composite structure phototransistor photodetector comprises the following steps:

[0015] (1) Transferring [TaSe4]2I nanowires onto a Si substrate;

[0016] The specific process is: [TaSe4]2I nanowires are transferred to a Si substrate with a SiO2 surface using polydimethylsiloxane (PDMS) tape.

[0017] (2) Transferring the MoTe2 nanofilm to one side of the [TaSe4]2I nanowire already placed on the Si substrate;

[0018] (3) Spin-coating photoresist uniformly on the surface of the Si substrate to prepare the pattern of the bottom electrode;

[0019] The rotation speed of the spin-coated photoresist is 3500 to 4500 rpm, and the spinning time is 30 to 40 seconds.

[0020] (4) Positioning and exposing the bottom electrode pattern, and then developing it to expose the portion where the electrode needs to be deposited;

[0021] (5) Preparation of metal electrodes;

[0022] The preparation process of [TaSe4]2I nanowires in step (1) is:

[0023] ① Prepare the ingredients according to the molar ratio of Ta:Se:I=2:8~8.1:1~2, put them into a quartz tube, mix them evenly, sinter and seal the tube after vacuuming;

[0024] The vacuum degree of the vacuum pumping is 3 to 5×10 -4 Pa.

[0025] ② Place the quartz tube in a heating furnace and gradually increase the temperature to allow the raw materials to fully react;

[0026] The staged heating is firstly heating to 120-150° C. over 10-15 hours and keeping the temperature constant for 5-20 hours; then heating to 600-700° C. over 10-25 hours and keeping the temperature constant for 25-35 hours.

[0027] ③ After the reaction is completed, the temperature of the heating furnace body is reduced to 400-500°C and kept at this temperature for 5-10 hours before being reduced to room temperature;

[0028] The furnace body is cooled at a rate of 0.2-2°C / hour.

[0029] ④ Take out the [TaSe4]2I bulk single crystal, place it in alcohol to remove the I attached to the surface, and then rinse it with deionized water;

[0030] ⑤ Mechanically exfoliate the [TaSe4]2I bulk single crystal to prepare [TaSe4]2I nanowires;

[0031] The specific process is: [TaSe4]2I bulk single crystal is transferred to Scotch tape, and then the tape is repeatedly folded and pasted. As the number of pastings increases, quasi-one-dimensional [TaSe4]2I nanowires of different thicknesses are continuously peeled off. The thinner the [TaSe4]2I nanowire, the lighter the color. As the color of the sample on the tape surface gradually becomes lighter, the bulk single crystal on the tape will be separated into thinner [TaSe4]2I nanowires.

[0032] The performance of the [TaSe₄]₂I and MoTe₂ composite device prepared using the aforementioned method was tested using a semiconductor testing system. A 440nm light source was used as the excitation light source. Under a 3V bias and a -10V gate voltage, the device demonstrated a high responsivity of 40A / W. At a -3V bias, the polarization ratio reached 3.6.

[0033] Although there are also photoelectric devices with composite structures of MoTe2 and other two-dimensional materials, their device performance is far inferior to the [TaSe4]2I and MoTe2 composite structure phototransistor detector prepared by the present invention.

[0034] The [TaSe4]2I and MoTe2 composite structure phototransistor detector of the present invention has achieved outstanding implementation results compared to other heterojunction photodetectors. Compared with photodetectors using only [TaSe4]2I, it shows higher responsivity, external quantum efficiency, detectivity, and polarization ratio (see Polarization-Sensitive Photodetector Based on Quasi-1D (TaSe4)2I Nanowire Response to 10.6μm, Adv. Funct. Mater. 2024, 34, 2315194.). Compared with photodetectors using only MoTe2, it also shows better responsivity and detectivity (see Highly sensitive visible to infrared MoTe2 photodetectors enhanced by the photogating effect, Nanotechnology 2016, 27, 445201.). Compared with other (quasi) one-dimensional / two-dimensional mixed heterojunctions (such as WS2 / 1DSb2Se3, MoS2 / 1D Ta2Pd3Se8, and MoS2 / 1D GaAsSb), the heterojunction phototransistor detector of the present invention also exhibits better sensitivity characteristics (see Direct van der Waals epitaxial growth of 1D / 2D Sb2Se3 / WS2mixed-dimensional pn heterojunctions, Nano Res. 2019, 12, 1139; Ultrafast Polarization Sensitive Photodetector Based on MoS2 / Ta2Pd3Se8Hybrid Dimensional Heterostructure, Adv. Optic. Mater. 2023, 11, 2300593; Mixed-Dimensional Anti-ambipolar Phototransistors Based on 1D GaAsSb / 2D MoS2Heterojunctions, ACS Nano 2022, 16, 11036).

[0035] Table 1 shows a comparison of the detector performance of the [TaSe4]2I and MoTe2 composite structure phototransistor detector of the present invention and other heterojunction photodetectors.

[0036] Table 1 Performance comparison of photodetectors with different 2D materials and structures

[0037]

[0038] The present invention utilizes the high carrier mobility and full-spectrum response characteristics of the quasi-one-dimensional semi-metallic material (TaSe4)2I, introduces the two-dimensional material MoTe2 to increase light absorption, and increases the carrier separation efficiency through the vertical structure of the heterojunction, thereby suppressing dark current and solving the shortcomings of single-material (TaSe4)2I photodetectors, such as large dark current and low switching ratio. Furthermore, through the back-gate phototransistor structure, the transport characteristics of channel carriers are regulated, and the photocurrent is increased to the μA level under negative gate voltage, achieving extremely high responsivity and external quantum efficiency, thereby greatly improving the sensitivity of the device and having ultra-sensitive detection capabilities. In addition, due to the improved carrier separation efficiency of the heterostructure, the polarization detection capability of the heterojunction photodetector is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector of the present invention.

[0040] Figure 2 This is an optical image of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector of the present invention.

[0041] Figure 3 The quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure prepared in Example 1 ( Figure 1 Dashed box 8) and (TaSe4)2I device structure ( Figure 1 Dashed box 6) and MoTe2 device structure ( Figure 1 Comparison of dark current output characteristic curves in the dashed box 7). The current value of (TaSe4)2I corresponds to the left Y-axis, and the current values ​​of MoTe2 and (TaSe4)2I / MoTe2 mixed-dimensional heterojunction correspond to the right Y-axis.

[0042] Figure 4 This is a photocurrent diagram of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector prepared in Example 1 at different gate voltages.

[0043] Figure 5 This is a diagram of the responsivity and detectivity of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector prepared in Example 1 under a gate voltage of -10V and a bias voltage of 3V.

[0044] Figure 6This is a time-current (IT) diagram of the polarization angle dependence of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector prepared in Example 1 under a bias of -3V.

[0045] Among them: 1. Si substrate, 2. SiO2 gate dielectric layer, 3. (TaSe4)2I nanowire, 4. MoTe2 nanofilm, 5. Metal electrode, 6. (TaSe4)2I single-material device, 7. MoTe2 single-material device, 8. (TaSe4)2I / MoTe2 heterojunction device, 9. Laser. DETAILED DESCRIPTION

[0046] like Figure 1 As shown, the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector of the present invention comprises, from bottom to top, a Si substrate 1, a SiO2 gate dielectric layer 2, a (TaSe4)2I nanowire 3, and a MoTe2 nanofilm 4. Metal electrodes 5 are provided on both the (TaSe4)2I nanowire 3 and the MoTe2 nanofilm 4. The MoTe2 nanofilm 4 is draped over the right side of the (TaSe4)2I nanowire 3. The Si substrate 1 is a heavily doped P-type silicon wafer with a surface SiO2 thickness of 280-300nm. The [TaSe4]2I nanowire 3 has a thickness of 50-200nm, and the MoTe2 nanofilm 4 has a thickness of 30-100nm. The metal electrode 5 comprises 3-5nm of chromium and 30-50nm of gold. The (TaSe4)2I nanowire 3 and a pair of electrodes thereon constitute a (TaSe4)2I single-material device 6. The MoTe2 nanofilm 4 and a pair of electrodes thereon constitute a MoTe2 single-material device 7. An electrode on the (TaSe4)2I nanowire 3 and an electrode on the MoTe2 nanofilm 4 form a (TaSe4)2I / MoTe2 heterojunction device 8 (ie, the composite structure phototransistor detector in the present invention).

[0047] Figure 2 The optical image of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 composite structure phototransistor detector of the present invention is given. The electrode pattern can be composed of three pairs of electrodes, one pair of which is designed on the (TaSe4)2I nanowire 3 (see Figure 1 A pair of electrodes in the dotted box indicated by the mark 6) and a pair of electrodes designed on the MoTe2 film 4 (see Figure 1 A pair of electrodes in the dotted box indicated by the mark 7 in FIG, one pair is designed on the (TaSe4)2I nanowire 3 and the other on the MoTe2 film 4 (see FIG. Figure 1 A pair of electrodes in the dotted box indicated by mark 8).

[0048] A two-dimensional MoTe2 nanofilm (4) is placed on one side of a (TaSe4)2I nanowire (3), creating a (TaSe4)2I / MoTe2 composite structure to suppress dark current. Silicon is used as the substrate, and SiO2 as the gate dielectric layer. Applying a gate voltage to the silicon modulates the photocurrent, thus achieving an ultra-sensitive photodetector.

[0049] The specific preparation process of the (TaSe4)2I / MoTe2 phototransistor of the present invention is described in detail below with reference to the accompanying drawings and examples.

[0050] Example 1

[0051] In this embodiment, a phototransistor detector having a composite structure of (TaSe4)2I nanowires 3 (TaSe4)2I with a thickness of 98 nm and MoTe2 nanofilm 4 with a thickness of 68 nm is prepared.

[0052] (1) Prepare the ingredients according to the molar ratio of Ta:Se:I=2:8.02:1.2, then put the raw materials into a quartz tube and evacuate to 3×10 -4 After sintering, seal the tube.

[0053] (2) Place the quartz tube in a heating furnace and heat it up in stages. First, heat it up to 120°C over 10 hours and keep it at this temperature for 15 hours. Then heat it up to 660°C over 15 hours and keep it at this temperature for 25 hours.

[0054] (3) Slowly cool the temperature to 500°C at a rate of 0.2°C / hour, during which (TaSe4)2I nucleates and grows; after maintaining the temperature for 5 hours, cool the temperature to room temperature to obtain a (TaSe4)2I bulk single crystal.

[0055] (4) After breaking the quartz tube, the (TaSe4)2I bulk single crystal was taken out and placed in ethanol to remove the raw material I attached to the surface. The resulting single crystal was then cleaned with deionized water to obtain a needle-shaped (TaSe4)2I bulk crystal with a metallic luster.

[0056] (5) Select a high-quality (TaSe4)2I bulk single crystal, then repeatedly fold and stick the tape (without removing the sample and re-sticking it). As the color of the sample on the tape gradually becomes lighter, the bulk single crystal on the tape will be separated into thinner (TaSe4)2I nanowires. Until a (TaSe4)2I nanowire with a thickness of 98nm is obtained.

[0057] (6) The (TaSe4)2I nanowires prepared by the above method were transferred to a heavily doped P-type silicon wafer with a surface of 290 nm thick SiO2 using PDMS tape.

[0058] (7) The MoTe2 was mechanically exfoliated using the same Scotch tape as in step (5) to obtain a 68 nm thick MoTe2 nanofilm.

[0059] (8) A portion of the obtained MoTe2 nanofilm is transferred to one side of the (TaSe4)2I nanowire 3 placed on the Si substrate using a transfer platform (see Figure 1 The other part of the MoTe2 nanofilm is directly placed on the SiO2 substrate 2 (see Figure 1 The dotted box indicated by mark 7 in FIG.

[0060] (9) Spin-coat AZ1500 photoresist onto the sample obtained in step (8) above using a spin coater and design and prepare an electrode pattern. The spin coater speed is 4000 rpm for 30 seconds.

[0061] For performance comparison, the electrode pattern can be composed of three pairs of electrodes, one pair of which is designed on the (TaSe4)2I nanowire 3 (see Figure 1 A pair of designs on the MoTe2 nanofilm 4 (see Figure 1 In the dotted box indicated by marker 7), an electrode on (TaSe4)2I and an electrode on MoTe2 form a pair of electrodes of the (TaSe4)2I / MoTe2 mixed-dimensional heterojunction (see Figure 1 The dotted box indicated by mark 8 in FIG.

[0062] (10) A laser direct writing lithography machine is used to expose the electrode pattern to prepare the electrode, and then the electrode pattern is exposed by developing with AZ400K developer.

[0063] (11) The samples obtained above were used to prepare metal electrodes using existing thermal evaporation technology, first evaporating 3 nm chromium and then evaporating 50 nm gold.

[0064] Figure 3 The photocurrent output characteristic curve of the (TaSe4)2I / MoTe2 composite structure phototransistor detector prepared in this embodiment is given, which is different from the (TaSe4)2I device structure ( Figure 1 Dashed box 6) and only MoTe2 device structure ( Figure 1 The dark current output characteristic curve of the dotted box 7) is compared. Figure 3 It can be seen that the dark current increases with increasing voltage, and under the same test conditions, the (TaSe4)2I / MoTe2 composite structure has a lower dark current than (TaSe4)2I and MoTe2.

[0065] Figure 4 The photocurrent diagram of the (TaSe4)2I / MoTe2 composite structure phototransistor detector prepared in this example at different gate voltages is given. Figure 4It can be seen that under the same test conditions, the net photocurrent is larger under negative gate voltage than under zero gate voltage, and increases with the increase of negative gate voltage.

[0066] The performance index test of the (TaSe4)2I / MoTe2 composite structure phototransistor detector prepared in this embodiment was carried out using a semiconductor testing system. Figure 5 The responsivity and detectivity of the (TaSe4)2I / MoTe2 composite structure phototransistor detector prepared in this example at different gate voltages are given. The laser with a wavelength of 440nm is used (see Figure 1 ) as the excitation light source, at a bias voltage of 3V and a gate voltage of -10V, the device's responsivity is as high as 40A / W, and the detection rate reaches 2.1×10 12 Jones.

[0067] Figure 6 The polarization detection capability of the (TaSe4)2I / MoTe2 composite structure phototransistor detector prepared in this example is demonstrated. Figure 1 ) as the excitation light source. Under a bias of -3V, the output current changes with the change of the polarization angle, and the polarization current ratio reaches 3.6.

[0068] Example 2

[0069] In this embodiment, a phototransistor detector having a composite structure of (TaSe4)2I nanowires 3 with a thickness of 110 nm and MoTe2 nanofilms 4 with a thickness of 47 nm is prepared.

[0070] (1) Prepare the ingredients according to the molar ratio of Ta:Se:I=2:8.05:1.5, then put the raw materials into a quartz tube and evacuate to 4×10 -4 After sintering, seal the tube.

[0071] (2) Place the quartz tube in a heating furnace and heat it up in stages. First, heat it up to 150°C over 12 hours and keep it at this temperature for 5 hours; then heat it up to 600°C over 20 hours and keep it at this temperature for 30 hours.

[0072] (3) Slowly cooling to 450°C at a rate of 1°C / hour, during which (TaSe4)2I nucleates and grows; after maintaining the temperature for 8 hours, cooling to room temperature to obtain a (TaSe4)2I bulk single crystal.

[0073] (4) After breaking the quartz tube, the (TaSe4)2I bulk single crystal was taken out and placed in ethanol to remove the raw material I attached to the surface. The resulting single crystal was then cleaned with deionized water to obtain a needle-shaped (TaSe4)2I bulk crystal with a metallic luster.

[0074] (5) Select high-quality MoTe2 bulk single crystals and use Scotch tape for mechanical exfoliation. The tape is repeatedly folded and pasted multiple times to obtain 110nm (TaSe4)2I nanowires.

[0075] (6) The (TaSe4)2I nanowires prepared by the above method were transferred to a heavily doped P-type silicon wafer with a surface of 280 nm thick SiO2 using PDMS tape.

[0076] (7) The MoTe2 was mechanically exfoliated using the same Scotch tape as in step (5) to obtain a 47 nm thick MoTe2 nanofilm.

[0077] (8) The obtained MoTe2 nanofilm is transferred to one side of the MoTe2 nanowire placed on the Si substrate with the assistance of a transfer platform.

[0078] (9) Spin-coat AZ1500 photoresist onto the sample obtained in step (8) above using a spin coater and design and prepare an electrode pattern. The spin coater speed is 3500 rpm and the time is 40 s.

[0079] (10) A laser direct writing lithography machine is used to expose the electrode pattern to prepare the electrode, and then the electrode pattern is exposed by developing with AZ400K developer.

[0080] (11) The samples obtained above were used to prepare metal electrodes using thermal evaporation technology, first evaporating 4 nm chromium and then evaporating 40 nm gold.

[0081] Example 3

[0082] In this embodiment, a phototransistor detector having a composite structure of (TaSe4)2I nanowires 3 with a thickness of 160 nm and MoTe2 nanofilms 4 with a thickness of 88 nm is prepared.

[0083] (1) Prepare the ingredients according to the molar ratio of Ta:Se:I=2:8.08:1.9, then put the raw materials into a quartz tube and evacuate to 5×10 -4 After sintering, seal the tube.

[0084] (2) Place the quartz tube in a heating furnace and heat it up in stages. First, heat it up to 135°C over 15 hours and keep it at that temperature for 20 hours. Then heat it up to 700°C over 25 hours and keep it at that temperature for 35 hours.

[0085] (3) Slowly cooling to 400°C at a rate of 2°C / hour, during which (TaSe4)2I nucleates and grows; after maintaining the temperature for 10 hours, cooling to room temperature to obtain a (TaSe4)2I bulk single crystal.

[0086] (4) After breaking the quartz tube, the (TaSe4)2I bulk single crystal was taken out and placed in ethanol to remove the raw material I attached to the surface. The resulting single crystal was then cleaned with deionized water to obtain a needle-shaped (TaSe4)2I bulk crystal with a metallic luster.

[0087] (5) Select high-quality (TaSe4)2I bulk single crystals and use Scotch tape for mechanical exfoliation. The tape is repeatedly folded and pasted multiple times to obtain 160nm (TaSe4)2I nanowires.

[0088] (6) The (TaSe4)2I nanofilm prepared by the above method was transferred to a heavily doped P-type silicon wafer with a surface of 300 nm thick SiO2 using PDMS tape.

[0089] (7) The MoTe2 was mechanically exfoliated using the same Scotch tape as in step (5) to obtain a MoTe2 nanofilm 88 nm thick.

[0090] (8) The obtained MoTe2 nanofilm is transferred to one side of the (TaSe4)2I nanowire placed on the Si substrate with the assistance of a transfer platform.

[0091] (9) Spin-coat AZ1500 photoresist onto the sample obtained in step (8) above using a spin coater and design and prepare an electrode pattern. The spin coater speed is 4500 rpm and the time is 35 s.

[0092] (10) A laser direct writing lithography machine is used to expose the electrode pattern to prepare the electrode, and then the electrode pattern is exposed by developing with AZ400K developer.

[0093] (11) The samples obtained above were used to prepare metal electrodes using thermal evaporation technology, first evaporating 5 nm of chromium and then evaporating 30 nm of gold.

[0094] Example 4

[0095] In this embodiment, a phototransistor detector having a composite structure of (TaSe4)2I nanowires 3 with a thickness of 200 nm and MoTe2 nanofilm 4 with a thickness of 100 nm is prepared.

[0096] The preparation process is the same as that of Example 3, except that in step (5) a (TaSe4)2I nanowire with a thickness of 200 nm is obtained, and in step (7) a MoTe2 nanofilm with a thickness of 100 nm is obtained.

[0097] Example 5

[0098] In this embodiment, a phototransistor detector having a composite structure of 50 nm thick ((TaSe4)2I nanowires 3 and 30 nm thick MoTe2 nanofilms 4 is prepared.

[0099] The preparation process is the same as that of Example 3, except that in step (5) a 50 nm thick (TaSe4)2I nanowire is obtained, and in step (7) a 30 nm thick MoTe2 nanofilm is obtained.

Claims

1. A method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector, characterized in that: The quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector comprises, from bottom to top, a Si substrate, a SiO2 gate dielectric layer, a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 nanofilm, and metal electrodes are respectively provided on the quasi-one-dimensional (TaSe4)2I and MoTe2 nanofilms to form a heterostructure of (TaSe4)2I, MoTe2 and metal electrodes; The preparation method of the quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector comprises the following steps: (1) Transferring (TaSe4)2I nanowires onto a Si substrate; (2) Transferring the MoTe2 nanofilm to one side of the (TaSe4)2I nanowire already placed on the Si substrate; (3) Spin-coat the photoresist evenly on the surface of the Si substrate to prepare the bottom electrode pattern; (4) Positioning and exposing the bottom electrode pattern, and then developing it to expose the portion where the electrode needs to be deposited; (5) Preparation of metal electrodes.

2. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The thickness of the (TaSe4)2I nanowires is 50 to 200 nm.

3. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The Si substrate is a heavily doped P-type silicon wafer with a surface SiO2 thickness of 280 to 300 nm.

4. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The thickness of the MoTe2 nanofilm is 30-100 nm.

5. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The metal electrodes are 3-5 nm chromium and 30-50 nm gold.

6. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The preparation process of [TaSe4]2I nanowires in step (1) is: ① Prepare the ingredients according to the molar ratio of Ta:Se:I=2:8~8.1:1~2, put them into a quartz tube and mix them evenly, then sinter and seal the tube after vacuuming; ② Place the quartz tube in a heating furnace and gradually increase the temperature to allow the raw materials to fully react; The staged heating is firstly heating to 120-150°C over 10-15 hours and keeping the temperature constant for 5-20 hours; then heating to 600-700°C over 10-25 hours and keeping the temperature constant for 25-35 hours; ③ After the reaction is completed, the temperature of the heating furnace body is reduced to 400-500°C and kept at this temperature for 5-10 hours before being reduced to room temperature; ④ Take out the [TaSe4]2I bulk single crystal, place it in alcohol to remove the I attached to the surface, and then rinse it with deionized water. net; ⑤ Mechanically exfoliate the [TaSe4]2I bulk single crystal to prepare [TaSe4]2I nanowires.

7. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 6, characterized in that: The specific process of step ⑤ is as follows: the [TaSe4]2I bulk single crystal is transferred to Scotch tape, and the tape is then repeatedly folded and pasted. As the number of pastings increases, quasi-one-dimensional [TaSe4]2I nanowires of varying thicknesses are continuously peeled off. The thinner the [TaSe4]2I nanowires, the lighter their color. As the color of the sample on the tape surface gradually lightens, the bulk single crystal on the tape will be separated into thinner [TaSe4]2I nanowires.

8. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: The specific process of transferring the [TaSe4]2I nanowires to the Si substrate in step (1) is as follows: the [TaSe4]2I nanowires are transferred to the Si substrate with a surface of SiO2 using polydimethylsiloxane (PDMS) tape as an aid.

9. The method for preparing a quasi-one-dimensional (TaSe4)2I and two-dimensional MoTe2 mixed-dimensional heterojunction phototransistor detector according to claim 1, characterized in that: In the step (3), the rotation speed of the spin-coating photoresist is 3500 to 4500 rpm, and the spinning time is 30 to 40 seconds.

Images