One-step preparation method for MoS2(Er) / WS2(Er) heterojunction photodetector

Abstract

The present invention provides a one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector, comprising: growing a MoS2(Er) / WS2(Er) heterojunction layer doped with a rare earth material on a SiO2 substrate by CVD; performing photolithography on the MoS2(Er) / WS2(Er) heterojunction layer according to a designed electrode pattern; performing magnetron sputtering on the photolithographic MoS2(Er) / WS2(Er) heterojunction layer to grow a metal electrode on the MoS2(Er) / WS2(Er) heterojunction layer; removing the photoresist to obtain the MoS2(Er) / WS2(Er) heterojunction photodetector. The present invention directly grows a heterojunction by CVD and dopes rare earth element Er ions, which helps to significantly improve the photoelectric efficiency and carrier concentration of the device.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic device manufacturing, and particularly relates to a MoS 2 (Er) / WS 2 (Er) One-step preparation method for heterojunction photodetector. Background Art

[0002] The traditional preparation of high-quality van der Waals heterostructures is the key to improving the performance of optoelectronic devices. Most of them use fixed-point transfer technology to prepare van der Waals heterojunctions, but PDMS is used in the fixed-point transfer process. In the experiment, PDMS is spin-coated onto the substrate on which the material is grown, and then peeled off in a sodium hydroxide solution. Through this step of treatment, the two-dimensional material will remain on the PDMS. Use PMMA to pick up the PDMS, wash it with deionized water, and then perform a fixed-point transfer under a microscope. After the transfer is completed, let it stand for one night, then soak it in an acetone solution to remove the PDMS on the surface. Then wash it with deionized water. The main pollution generated in this process is sodium ions, the hydroxide ions are not handled cleanly, the PDMS glue is not handled cleanly, and acetone residues. In addition, during the transfer process, the two-dimensional material is not completely stretched, and wrinkles that are invisible to the naked eye will be produced, which will greatly affect the contact between the materials and will inevitably introduce impurities, thereby affecting the optoelectronic properties of the heterojunction.

[0003] Therefore, most of the existing van der Waals heterostructures are directly grown by CVD. This method can directly grow vertical or lateral heterojunctions, avoiding the performance impact of impurities on the van der Waals heterojunction. Although the preparation of high-quality van der Waals heterostructures is the key to improving the performance of optoelectronic devices, most of them use fixed-point transfer technology to prepare van der Waals heterojunctions because the micro-area fixed-point transfer technology is convenient and fast. However, impurities will inevitably be introduced during the transfer process, thus affecting the optoelectronic performance of the heterojunction. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a MoS 2 (Er) / WS 2 (Er) A one-step preparation method of a heterojunction photodetector, comprising:

[0005] S1: SiO 2 MoS doped with rare earth materials was grown on substrates by CVD 2 (Er) / WS 2 (Er) heterojunction layer;

[0006] S2: MoS based on the designed electrode pattern 2 (Er) / WS 2 (Er) photolithography of the heterojunction layer;

[0007] S3: MoS after photolithography 2 (Er) / WS 2 (Er) heterojunction layer was magnetron sputtered to form MoS 2 (Er) / WS 2 (Er) growing a metal electrode on the heterojunction layer;

[0008] S4: Remove the photoresist to obtain MoS 2 (Er) / WS 2 (Er) Heterojunction photodetector.

[0009] Preferably, the SiO 2 Growth of MoS on substrate 2 (Er) / WS 2 (Er) Heterojunction layer includes:

[0010] S11: SiO 2 The substrate is ultrasonically cleaned to remove surface impurities;

[0011] S12: dissolving sodium molybdate, sodium tungstate and sodium hydroxide in deionized water to prepare a mixed solution; dissolving erbium chloride hexahydrate in deionized water to prepare an erbium chloride aqueous solution;

[0012] S13: dropping the hydrogen peroxide solution into the concentrated sulfuric acid solution to prepare a piranha solution;

[0013] S14: The SiO 2 The substrate was placed in the prepared piranha solution and heated at 150°C for 30 minutes. After the treatment, the SiO 2 The piranha solution is applied to the substrate surface and then dried;

[0014] S15: drying the SiO 2 The substrate is placed in a coating machine and the erbium chloride aqueous solution is spin-coated. After the spin coating is completed, the SiO 2 The substrate is placed in a coating machine, and the mixed solution is spin-coated, and then dried after the spin coating is completed;

[0015] S16: Put the sulfur powder into a quartz boat and place it in the heating temperature zone 1 of the tube furnace to 2 The substrate is placed on a quartz boat and placed in heating temperature zone 2 of a tube furnace;

[0016] S17: Close the inlet valve and outlet valve of the tubular furnace, open the vacuum pump to extract the impurities to a vacuum state, then open the inlet valve to introduce Ar gas to restore to normal pressure, then start the heating temperature zone 1 and heating temperature zone 2 of the tubular furnace, open the inlet valve and outlet valve at the same time and introduce Ar gas at a flow rate of 60 sccm. When the preset growth temperature is about to be reached, change to introduce Ar / H at a flow rate of 60 sccm. 2 After the growth is completed, the mixture is naturally cooled to 600°C and then replaced with Ar gas at a flow rate of 60sccm, and then naturally cooled to room temperature.

[0017] Preferably, the heating temperature zone 1 is close to the air inlet valve of the tubular furnace; and the heating temperature zone 2 is close to the air outlet valve of the tubular furnace.

[0018] Preferably, the mixed solution is prepared by dissolving 25 mg of sodium molybdate, 25 mg of sodium tungstate and 23 mg of sodium hydroxide in 10 ml of deionized water.

[0019] Preferably, the aqueous solution of erbium chloride is prepared by dissolving 170 mg of erbium chloride hexahydrate in 10 ml of deionized water.

[0020] Preferably, the piranha solution is prepared by dropping 9 ml of hydrogen peroxide solution into 21 ml of concentrated sulfuric acid solution.

[0021] Preferably, the heating temperature zone 1 of the tubular furnace is kept at room temperature for 20 minutes, then raised to 200°C within 10 minutes, kept for 30 minutes, and then naturally cooled to room temperature; the heating temperature zone 2 of the tubular furnace is raised from room temperature to 750°C within 30 minutes, kept for 10 minutes, and then raised to 850°C within 10 minutes, kept for 10 minutes, and finally cooled to room temperature.

[0022] Preferably, the preset growth temperature is 800°C.

[0023] Preferably, the electrode pattern designed for MoS 2 (Er) / WS 2 (Er) Photolithography of heterojunction layer includes:

[0024] S21: In MoS 2 (Er) / WS 2 (Er) spin coating a first layer of LOR photoresist on the heterojunction layer and performing soft baking;

[0025] S22: spin-coating a second layer of S1805 photoresist on the first layer of LOR photoresist, and performing soft baking;

[0026] S23: MoS based on the designed electrode pattern 2 (Er) / WS 2(Er) The heterojunction layer is directly written by laser, and the deteriorated photoresist caused by exposure is removed by development and shaping, and then rinsed with deionized water to remove the residual developer, and then blown dry with a nitrogen gun.

[0027] Preferably, the removing of the photoresist comprises: dissolving the second layer of S1805 photoresist by acetone, dissolving the first layer of LOR photoresist by AZ300 developer, rinsing by deionized water, drying by nitrogen gun, and finally drying.

[0028] The present invention has at least the following beneficial effects

[0029] The present invention directly grows the heterojunction through CVD, which can effectively avoid the problems generated in the transfer process, and at the same time avoids the lattice distortion that may occur in the transfer process, greatly improving the photoelectric performance of the heterojunction, and the incorporation of the rare earth element Er ions can effectively fill the tungsten vacancies, thereby inhibiting non-radiative recombination; at the same time, the 4f energy level electrons rich in Er ions can effectively increase the free electron state density of the two-dimensional material, so that the luminescence peak intensity of the sample after doping with Er ions is multiplied by an order of magnitude, and the incorporation of Er ions with active and rich electronic energy levels helps to significantly improve the photoelectric efficiency and carrier concentration of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0031] Figure 2 A schematic diagram showing the comparison of the photoelectric performance of the photodetector prepared by MoS2(Er) / WS2(Er) in the present invention and the photodetector prepared by other materials;

[0032] Figure 3 In the preparation process of the present invention, different concentrations of sodium hydroxide are used to treat MoS 2 (Er) / WS 2 (Er) Schematic diagram of the effect of heterojunction growth;

[0033] Figure 4 MoS prepared by traditional powder method 2 / WS 2 Optical micrograph of a vertical heterojunction and its IV curve;

[0034] Figure 5 The MoS prepared in the present invention 2 (Er) / WS 2 (Er) Optical micrograph of the vertical heterojunction and its IV curve. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0037] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] See also Figure 1 The present invention provides a MoS 2 (Er) / WS 2 (Er) A one-step preparation method of a heterojunction photodetector, comprising:

[0039] S1: SiO 2 MoS doped with rare earth materials was grown on substrates by CVD 2 (Er) / WS 2 (Er) heterojunction layer;

[0040] S2: MoS based on the designed electrode pattern 2 (Er) / WS 2 (Er) photolithography of the heterojunction layer;

[0041] S3: MoS after photolithography 2 (Er) / WS 2 (Er) heterojunction layer was magnetron sputtered to form MoS 2(Er) / WS 2 (Er) growing a metal electrode on the heterojunction layer;

[0042] S4: Remove the photoresist to obtain MoS 2 (Er) / WS 2 (Er) Heterojunction photodetector.

[0043] In this embodiment, the incorporation of rare earth element Er ions can effectively fill tungsten vacancies, thereby inhibiting non-radiative recombination; at the same time, the 4f energy level electrons rich in Er ions can effectively increase the free electron state density of the two-dimensional material, so that the peak luminescence intensity of the sample after doping with Er ions is multiplied by an order of magnitude; the incorporation of Er ions with active and rich electronic energy levels helps to significantly improve the photoelectric efficiency and carrier concentration of the device, please refer to Figure 2 , Figure 2 The photoelectric performance comparison results of the photoelectric detector proposed in the present invention and the photoelectric detectors made of several other materials are given. The preparation method of the photoelectric detector is mostly prepared by the CVD method. Figure 2 It can be seen that the photodetector prepared in this experiment has excellent performance in terms of photoelectric performance parameters; for the light response R λ , than the lowest MoS 2 / WS 2 (Ref1) is nearly 700,000 times higher. In terms of external quantum efficiency EQE, it is about WS 2 / MoS 2 (Ref4) is 12 times higher than the lowest MoS 2 / WS 2 (Ref1) is 5708 times higher. In terms of the specific detectivity D*, it can be seen that it is about SnS 2 / MoS 2 (Ref8) is 3 times the vertical heterojunction, about MoS 2 / WS 2 By comparing the photoelectric performance parameters, it can be seen that the device prepared in this experiment has greatly improved the photoelectric performance level due to the rare earth element Er ion doping.

[0044] Preferably, the SiO 2 Growth of MoS on substrate 2 (Er) / WS 2 (Er) Heterojunction layer includes:

[0045] S11: SiO 2 The substrate is ultrasonically cleaned to remove surface impurities;

[0046] A specific implementation of step S11 includes: firstly using a laser cutting machine to cut SiO 2The substrate was cut into 1 cm × 2 cm pieces to prepare SiO 2 Substrate: Place the cut silicon wafer in a beaker and use acetone, ethanol, and deionized water to ultrasonically treat the substrate for 10 minutes respectively to remove surface impurities.

[0047] S12: dissolving sodium molybdate, sodium tungstate and sodium hydroxide in deionized water to prepare a mixed solution; dissolving erbium chloride hexahydrate in deionized water to prepare an erbium chloride aqueous solution;

[0048] A specific implementation of step S12 includes: using a measuring balance, weighing 25 mg of sodium molybdate, 25 mg of sodium tungstate, and 23 mg of sodium hydroxide and dissolving them in 10 ml of deionized water to prepare an aqueous solution of erbium chloride.

[0049] S13: dropping the hydrogen peroxide solution into the concentrated sulfuric acid solution to prepare a piranha solution;

[0050] A specific implementation of step S13 includes: dropping 9 ml of hydrogen peroxide solution into 21 ml of concentrated sulfuric acid solution to prepare a piranha solution.

[0051] This example explores the effect of different concentrations of sodium hydroxide on the growth of vertical heterojunctions. It can be seen that in the case of 0 mg / ml, no vertical heterojunction grows, and as the concentration of sodium hydroxide continues to increase, it can be seen that a heterojunction gradually appears. At a concentration of about 2.3 mg / ml and 2.5 mg / ml, a vertical heterojunction with a clear double-layer structure can be grown, and as the concentration further increases, it can be seen that a stacking phenomenon occurs, tending to grow a multi-layer structure. This figure aims to explore the optimal sodium hydroxide growth concentration. It can be seen that sodium hydroxide has a maximum effect on the growth of vertical heterojunctions, from Figure 3 It can be seen that the sodium hydroxide concentration between 2.3 mg / ml and 2.5 mg / ml has the best effect on generating a vertical heterojunction of a double-layer structure.

[0052] S14: The SiO 2 The substrate was placed in the prepared piranha solution and heated at 150°C for 30 minutes. After the treatment, the SiO 2 The piranha solution is applied to the substrate surface and then dried;

[0053] A specific implementation of step S14 includes: 2 The substrate is placed in the prepared piranha solution and heated at 150°C for 30 minutes to improve the hydrophilicity of the substrate. The treated substrate is rinsed with deionized water to remove the piranha solution on the surface, and then heated to dry the surface moisture.

[0054] S15: drying the SiO 2 The substrate is placed in a coating machine and the erbium chloride aqueous solution is spin-coated. After the spin coating is completed, the SiO 2 The substrate is placed in a coating machine, and the mixed solution is spin-coated, and then dried after the spin coating is completed;

[0055] A specific implementation of step S15 includes: treating the SiO 2 The substrate is placed in a coater, and an aqueous solution of erbium chloride is first dripped into it. The speed is set to 8000 r / min for 30 s. After the spin coating is completed, heat treatment is performed to dry the surface moisture. The dried substrate is placed in the coater again, and the mixed solution is dripped into it. The speed is set to 8000 r / min for 30 s. After the spin coating is completed, heat treatment is performed to dry the surface moisture.

[0056] S16: Put the sulfur powder into a quartz boat and place it in the heating temperature zone 1 of the tube furnace to 2 The substrate is placed on a quartz boat and placed in heating temperature zone 2 of a tube furnace;

[0057] S17: Close the inlet valve and outlet valve of the tubular furnace, open the vacuum pump to extract the impurities to a vacuum state, then open the inlet valve to introduce Ar gas to restore to normal pressure, then start the heating temperature zone 1 and heating temperature zone 2 of the tubular furnace, open the inlet valve and outlet valve at the same time and introduce Ar gas at a flow rate of 60 sccm. When the preset growth temperature is about to be reached, change to introduce Ar / H at a flow rate of 60 sccm. 2 After the growth is completed, the mixture is naturally cooled to 600°C and then replaced with Ar gas at a flow rate of 60sccm, and then naturally cooled to room temperature.

[0058] A specific implementation of step S17 includes: the temperature zone 1 of the tubular furnace is first kept at room temperature for 20 minutes, then raised to 200°C within 10 minutes, kept for 30 minutes, and then naturally cooled to room temperature; the temperature zone 2 is raised from room temperature to 750°C within 30 minutes, and kept for 10 minutes, and then raised to 850°C within 10 minutes, and kept for 10 minutes, and finally cooled to room temperature; the inlet valve and outlet valve of the tubular furnace are closed, the vacuum pump is opened to extract the impurities to a vacuum state, and then the inlet valve is opened to introduce Ar gas to restore to normal pressure, and the operation is repeated twice to better remove impurities. After the gas washing is completed, the two heating zones of the tubular furnace are started, and the inlet valve and outlet valve are opened at the same time, and Ar gas is introduced at a flow rate of 60sccm. When the growth temperature is about to be reached, change to Ar / H 2 Mixed gas, keep the flow rate constant. After the growth is completed, it is naturally cooled to 600℃ and replaced with Ar gas. Then it is naturally cooled to room temperature.

[0059] Sodium molybdate solution begins to react with S vapor at 750°C to generate MoS 2 , the reaction time is 10min' for a full reaction. Then the temperature rises to 850℃, and the sodium tungstate solution begins to react with the S vapor. Since the binding energy between the two-dimensional material and the substrate is greater than the van der Waals force between them, WS 2 Prefer to be in MoS 2 To grow.

[0060] The heating temperature zone 1 is close to the air inlet valve of the tubular furnace; the heating temperature zone 2 is close to the air outlet valve of the tubular furnace.

[0061] Preferably, the preset growth temperature is 800°C.

[0062] Preferably, the heating temperature zone 1 of the tubular furnace is kept at room temperature for 20 minutes, then raised to 200°C within 10 minutes, kept for 30 minutes, and then naturally cooled to room temperature; the heating temperature zone 2 of the tubular furnace is raised from room temperature to 750°C within 30 minutes, kept for 10 minutes, and then raised to 850°C within 10 minutes, kept for 10 minutes, and finally cooled to room temperature.

[0063] Preferably, the mixed solution is prepared by dissolving 25 mg of sodium molybdate, 25 mg of sodium tungstate and 23 mg of sodium hydroxide in 10 ml of deionized water.

[0064] Preferably, the electrode pattern designed for MoS 2 (Er) / WS 2 (Er) Photolithography of heterojunction layer includes:

[0065] S21: In MoS 2 (Er) / WS 2 (Er) spin coating a first layer of LOR photoresist on the heterojunction layer and performing soft baking;

[0066] In this embodiment, spin coating the first layer of LOR photoresist includes two stages: the specific parameters are set as: the first stage speed is 500 rpm, the time is 5 s; the second stage speed is 3500 rpm, the time is 35 s; the sample is baked in a 170°C drying machine for 10 minutes to remove excess moisture in the photoresist and increase the adhesion between the photoresist and the substrate.

[0067] S22: spin-coating a second layer of S1805 photoresist on the first layer of LOR photoresist, and performing soft baking;

[0068] In this embodiment, a spin coater is used to spin coat the second layer of S1805 photoresist, and the specific parameters are: 500 rpm for 5 seconds in the first stage; 2000 rpm for 25 seconds in the second stage; 3000 rpm for 3 seconds in the third stage, and the sample is baked in a drying machine at 100°C for 10 minutes.

[0069] S23: MoS based on the designed electrode pattern 2 (Er) / WS 2 (Er) the heterojunction layer is directly written by laser, and the deteriorated photoresist caused by exposure is removed by developing and finalizing, and the layer is rinsed with deionized water to remove the residual developer, and then dried with a nitrogen gun;

[0070] In this embodiment, removing the deteriorated photoresist caused by exposure includes: developing in AZ300 developer for 60 seconds to remove the deteriorated photoresist caused by exposure, then rinsing the sample with deionized water to remove the residual developer. Finally, drying with a nitrogen gun, and performing magnetron sputtering using a sputtering coating machine. The sputtered metal electrode is gold with a thickness of 50nm.

[0071] Preferably, the removing of the photoresist comprises: dissolving the second layer of S1805 photoresist by acetone, dissolving the first layer of LOR photoresist by AZ300 developer, rinsing by deionized water, drying by nitrogen gun, and finally drying.

[0072] See also Figure 4 and Figure 5 , Figure 4 MoS grown and transferred by powder method 2 / WS 2 The vertical heterojunction optical micrograph and its IV curve show that the vertical heterojunction has an obvious rectifying effect. At V = 2V, the laser power density is 181mW / cm 2 Under the conditions, the current is 0.69uA; Figure 5 The vertical MoS2(Er) / WS2(Er) heterojunction directly grown by the one-step method of the present invention can be seen that the photoelectric performance of the device is greatly improved by the one-step preparation and the addition of the Er element. Under the conditions of V=2V and a laser power density of 181mW / cm2, the current is 43uA. Under the same conditions, the current increases by about 62.3 times, indicating that the performance has been greatly improved by the addition of the Er element and the one-step preparation.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A one-step preparation method for a MoS2(Er) / WS2(Er) heterojunction photodetector, characterized in that: include: S1: MoS2(Er) / WS2(Er) heterojunction layer doped with rare earth materials was grown on SiO2 substrate by CVD; Growing MoS2(Er) / WS2(Er) heterojunction layer on SiO2 substrate includes: S11: ultrasonically clean the SiO2 substrate to remove surface impurities; Step S11 includes: firstly, using a laser cutting machine to cut the SiO2 substrate to a size of 1 cm×2 cm to prepare a SiO2 substrate, placing the cut silicon wafer into a beaker and using acetone, ethanol, and deionized water to perform ultrasonic treatment on the substrate for 10 minutes respectively to remove surface impurities; S12: dissolving sodium molybdate (Na2MoO4), sodium tungstate (Na2WO4) and sodium hydroxide (NaOH) in deionized water to prepare a mixed solution; dissolving erbium chloride hexahydrate in deionized water to prepare an aqueous solution of erbium chloride; S13: dropping the hydrogen peroxide solution into the concentrated sulfuric acid solution to prepare a piranha solution; S14: placing the SiO2 substrate after ultrasonic cleaning into the prepared piranha solution and heating it at 150° C. for 30 minutes. After the treatment is completed, removing the piranha solution on the surface of the SiO2 substrate and drying it; S15: placing the SiO2 substrate dried in step S14 into a coating machine, spin coating the aqueous solution of erbium chloride, and drying it after the coating is completed. Then placing the dried SiO2 substrate into a coating machine again, spin coating the mixed solution, and drying it after the coating is completed. S16: Put the sulfur powder into a quartz boat and place it in the heating temperature zone 1 of the tube furnace, and place the SiO2 substrate processed in step S15 on the quartz boat and place it in the heating temperature zone 2 of the tube furnace; S17: Close the inlet valve and outlet valve of the tubular furnace, open the vacuum pump to extract the impurities to a vacuum state, then open the inlet valve to introduce Ar gas to restore to normal pressure, then start the heating temperature zone 1 and heating temperature zone 2 of the tubular furnace, open the inlet valve and outlet valve at the same time and introduce Ar gas at a flow rate of 60 sccm. When the preset growth temperature is about to be reached, change to introduce Ar / H2 mixed gas at a flow rate of 60 sccm. After the growth is completed, naturally cool to 600°C, switch back to introducing Ar gas at a flow rate of 60 sccm, and then naturally cool to room temperature; S2: Photolithography of the MoS2(Er) / WS2(Er) heterojunction layer according to the designed electrode pattern; S3: magnetron sputtering the MoS2(Er) / WS2(Er) heterojunction layer after photolithography to grow a metal electrode on the MoS2(Er) / WS2(Er) heterojunction layer; S4: remove the photoresist to obtain a MoS2(Er) / WS2(Er) heterojunction photodetector.

2. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The heating temperature zone 1 is close to the air inlet valve of the tubular furnace; the heating temperature zone 2 is close to the air outlet valve of the tubular furnace.

3. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The mixed solution is prepared by dissolving 25 mg of sodium molybdate, 25 mg of sodium tungstate and 23 mg of sodium hydroxide in 10 ml of deionized water.

4. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The aqueous solution of erbium chloride is prepared by dissolving 170 mg of erbium chloride hexahydrate in 10 ml of deionized water.

5. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The piranha solution is prepared by dropping 9 ml of hydrogen peroxide solution into 21 ml of concentrated sulfuric acid solution.

6. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The heating temperature zone 1 of the tubular furnace is kept at room temperature for 20 minutes, then raised to 200°C within 10 minutes, kept at this temperature for 30 minutes, and then naturally cooled to room temperature; the heating temperature zone 2 of the tubular furnace is raised from room temperature to 750°C within 30 minutes, kept at this temperature for 10 minutes, then raised to 850°C within 10 minutes, kept at this temperature for 10 minutes, and finally cooled to room temperature.

7. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The preset growth temperature is 800°C.

8. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 1, characterized in that: The photolithography of the MoS2(Er) / WS2(Er) heterojunction layer according to the designed electrode pattern comprises: S21: spin coating the first layer of LOR photoresist on the MoS2(Er) / WS2(Er) heterojunction layer and soft baking; S22: spin-coating a second layer of S1805 photoresist on the first layer of LOR photoresist, and performing soft baking; S23: Laser direct writing is performed on the MoS2(Er) / WS2(Er) heterojunction layer according to the designed electrode pattern, and the deteriorated photoresist caused by exposure is removed by development and shaping, and then the residual developer is removed by rinsing with deionized water, and then the layer is dried with a nitrogen gun.

9. The one-step preparation method of a MoS2(Er) / WS2(Er) heterojunction photodetector according to claim 8, characterized in that: The photoresist removal includes: dissolving the second layer of S1805 photoresist by acetone, dissolving the first layer of LOR photoresist by AZ300 developer, rinsing by deionized water, drying by nitrogen gun, and finally drying.

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