A photoelectric memristor based on van der Waals heterojunction and its fabrication method

Abstract

This invention provides a van der Waals heterojunction-based photoelectric memristor and its fabrication method. The structure of the photoelectric memristor, from bottom to top, includes: a niobium-doped strontium titanate conductive substrate layer, a Bi₂Te layer, and a [missing information - likely a specific layer or structure]. 3‑x Se x / SnSe y Superimposed functional layer and Pd top electrode layer; wherein, 0 < x < 3, 0.6 < y < 2; Bi2Te 3‑x Se x / SnSe y The overlay functional layer includes the lower SnSe layer. y and the upper Bi2Te 3‑x Se x This invention is the first to use bismuth telluride selenide / tin selenide as the intermediate functional layer of an opto-memristor. It has photodetection characteristics, and a single device can achieve efficient storage and long-wavelength photodetection functions. At the same time, it also has good P-E hysteresis loop durability and stable I-V characteristics. It is a high-stability opto-memristor with excellent storage performance, good infrared stability, high sample yield, and broader application prospects.

Description

Technical Field

[0001] This invention relates to the field of memory technology, specifically to a photoelectric memristor based on a van der Waals heterojunction and its fabrication method. Background Technology

[0002] A memristor is a circuit device that represents the relationship between magnetic flux and electric charge; its full name is memory resistor. A memristor has the dimension of resistance, but unlike a regular resistor, its resistance value is determined by the charge flowing through it. Therefore, by measuring the resistance of a memristor, the amount of charge flowing through it can be determined, thus enabling it to "remember" charge. As the fourth fundamental circuit element, memristors are widely used in many fields such as information storage, logic operations, neural networks, and machine learning, and have become a hot research topic.

[0003] Van der Waals heterostructures (vdWHs) are layered structures that bind two-dimensional materials together by van der Waals forces. There are no chemical bonds between the different layers of a vdWH; they are held together solely by van der Waals forces. VdWHs not only retain the excellent properties of the original two-dimensional materials but also acquire some new and unique properties. Currently, vdWHs have become a hot research topic.

[0004] Chinese patent application (201810888810.3) discloses a van der Waals heterojunction memristor based on black phosphorus and black phosphorus oxide. The basic structure of the memristor, from bottom to top, includes a substrate, a bottom electrode layer, a resistive switching functional layer, and a top electrode layer; wherein, the resistive switching functional layer is composed of black phosphorus (BP) and black phosphorus oxide (P4O). x A van der Waals heterostructure was formed, and metal ions were incorporated into this heterostructure. BP and P4O were designed utilizing the characteristic that black phosphorus readily oxidizes to phosphorus oxide. x Van der Waals heterojunctions transform the shortcomings of black phosphorus in applications into usable advantages. Simultaneously, they utilize BP and P4O... x The cation-binding effect and variable conductivity of van der Waals heterojunctions were used to design van der Waals memristors based on black phosphorus and black phosphorus oxide. Summary of the Invention

[0005] The purpose of this invention is to provide a van der Waals heterojunction-based optoelectronic memristor and its fabrication method. This optoelectronic memristor uses two-dimensional ferroelectric materials bismuth telluride selenide / tin selenide to form a van der Waals heterojunction, which can achieve efficient storage and long-wavelength optical detection functions.

[0006] This invention is implemented as follows:

[0007] A photoelectric memristor based on a van der Waals heterojunction comprises, from bottom to top: a niobium-doped strontium titanate conductive substrate layer, a Bi₂Te layer, and a strontium titanate conductive substrate layer.3-x Se x / SnSe y Superimposed functional layer and Pd top electrode layer; wherein, 0 < x < 3, 0.6 < y < 2; Bi2Te 3- x Se x / SnSe y The overlay functional layer is composed of SnSe y Functional layer and Bi2Te 3-x Se x Bi2Te is formed by stacking functional layers together. 3-x Se x The functional layer is located in SnSe y On the functional layer; Bi2Te 3-x Se x / SnSe y Stacking functional layers constitutes a van der Waals heterostructure.

[0008] Preferred, SnSe y The functional layer thickness is 8–16 nm, Bi2Te 3-x Se x The thickness of the functional layer is 10–30 nm, and the thickness of the Pd top electrode layer is 30–60 nm.

[0009] Preferably, the Pd top electrode layer comprises a plurality of uniformly distributed layers on Bi2Te. 3－x Se x / SnSe y Circular electrodes on a superimposed functional layer.

[0010] This invention also provides a method for fabricating a photoelectric memristor based on a van der Waals heterojunction, specifically including the following steps:

[0011] (1) Preparation of SnSe y Target material: Particulate Sn and Se are mixed in a set ratio, calcined in a muffle furnace, cooled, ground, and then the ground tin selenide powder is calcined in a plasma sintering furnace to obtain SnSe. y Target material; 0.6 < y < 2;

[0012] (2) Preparation of Bi2Te 3-x Se x Target material: Particulate Bi, Te, and Se are mixed in a predetermined ratio, calcined in a muffle furnace, cooled, ground, and then calcined in a plasma sintering furnace to obtain Bi2Te. 3-x Se x Target material; 0 < x < 3;

[0013] (3) The niobium-doped strontium titanate (NSTO) conductive substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water, and then dried with nitrogen.

[0014] (4) Preparation of Bi2Te 3-x Se x / SnSe y Superimposed functional layer: SnSe is formed on a niobium-doped strontium titanate conductive substrate using pulsed laser deposition. y Functional layer, then in SnSe y Bi2Te is formed on the functional layer 3-x Se x Functional layer; SnSe y Functional layer and Bi2Te 3-x Se x Functional layers are stacked together to form Bi2Te 3-x Se x / SnSe y Overlay functional layers;

[0015] (5) Preparation of Pd top electrode layer: In Bi2Te 3-x Se x / SnSe y A photomask with 100-micrometer diameter circular holes is attached to the superimposed functional layer. The Bi2Te layer is then deposited using magnetron sputtering. 3-x Se x / SnSe y A Pd top electrode layer is formed by sputtering on the superimposed functional layer.

[0016] Preferably, in step (1), the ratio of granular Sn and Se is Sn:Se = 1:1 to 1:5. Sn and Se are calcined in a muffle furnace at 600 to 950°C for 24 hours, then cooled for 24 hours, ball-milled, and then the ball-milled tin selenide powder is calcined again in a plasma sintering furnace at 40 to 50 MPa and 400 to 525°C.

[0017] In step (2), granular Bi, Te and Se are calcined in a muffle furnace at 600-950℃ for 24h, then cooled for 24h, ball-milled, and then the ball-milled bismuth tellurium selenide powder is calcined again in a plasma sintering furnace at 40-50MPa and 400-525℃.

[0018] Preferably, in step (4), SnSe is prepared y For functional layers, the parameters for pulsed laser deposition are: adjust the appropriate target spacing and evacuate the cavity to a back-bottom vacuum of 2×10⁻⁶. -4Below Pa, heat the sample stage to 50–500°C, introduce argon gas into the cavity to maintain a pressure of 0.1–3 Pa, turn on the excimer laser, and adjust the laser energy density to 1.5–3 J / cm². 2 The laser frequency is 1–5 Hz, so that the laser passes through a lens and strikes SnSe. y Pre-sputtering at the target center for 1 min; followed by formal sputtering for 30–60 min; preparation of Bi2Te 3-x Se x For the functional layer, the parameters for the pulsed laser deposition process are: the cavity is evacuated back to a vacuum of 2 × 10⁻⁶. -4 When the pressure is below 10 Pa, argon gas is introduced into the cavity, and the gate valve is adjusted to maintain the pressure in the cavity at 10–40 Pa. Then, Bi2Te gas is replaced. 3－x Se x Set the target material, turn on the excimer laser, and adjust the laser energy density to 1.2–3 J / cm². 2 The laser frequency is 1-5 Hz, so that the laser passes through a lens and hits Bi2Te. 3－x Se x Pre-sputtering at the target center for 1 minute; followed by formal sputtering for 5–15 minutes on SnSe. y Bi2Te is formed on the functional layer 3－x Se x Functional layer.

[0019] Preferably, in step (5), when preparing the Pd top electrode layer, the parameters of the magnetron sputtering process are: evacuating the cavity to a vacuum of 1.8 × 10⁻⁶. -4 Argon gas is introduced into the chamber at Pa, and the pressure inside the chamber is adjusted to maintain 0.1-20 Pa. The DC source controlling the ignition of the palladium target is turned on, and the power of the DC source is adjusted to 5-20 W to ignite the palladium target. Pre-sputtering is performed for 1 minute, followed by formal sputtering for 15-30 minutes in Bi2Te. 3－x Se x / SnSe y A Pd top electrode layer is formed on the superimposed functional layer.

[0020] In the above preparation method, the SnSe formed in step (4) y The thickness of the functional layer is 8–16 nm, forming Bi2Te 3－x Se x The thickness of the functional layer is 10–30 nm.

[0021] In the above preparation method, the mask in step (5) has circular holes evenly distributed on it.

[0022] In the above preparation method, the Pd top electrode layer in step (5) comprises several uniformly distributed layers on Bi2Te. 3－x Se x / SnSey A circular electrode is superimposed on the functional layer; its thickness is 30-60 nm.

[0023] In this invention, the NSTO, Sn, Se, Bi, Te, and Pd materials are commercially available products.

[0024] The photoelectric memristor based on a van der Waals heterojunction provided by this invention utilizes the two-dimensional ferroelectric material bismuth telluride selenide / tin selenide. Bismuth telluride selenide and tin selenide form a superimposed functional layer and constitute a van der Waals heterojunction, resulting in excellent device performance. A series of electrical performance tests were conducted on the memristor prepared in this invention. Applying voltage caused the ferroelectric domains of the superimposed functional layer to reverse polarization, thereby changing the device's resistance. Bismuth telluride selenide (Bi₂Te₅) 3－x Se x The material is both a photosensitive medium and a storage medium. Therefore, the photoelectric memristor made using this material not only has storage function, but also has photoresponse characteristics.

[0025] The photoresistor based on a van der Waals heterojunction provided by this invention, compared with the device in Chinese patent application (201810888810.3), has the advantages of simple fabrication structure and good electrical stability (e.g., Figure 4 The paper demonstrates 840 IV cycles and high sample yield (e.g., ...). Figure 5 As shown), it responds to visible and infrared light (e.g. Figure 6 (as shown) and has good infrared light response stability (e.g. Figure 7 (as shown) and other advantages. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the opto-memristor based on the van der Waals heterojunction provided by the present invention.

[0027] Figure 2 This is an AFM morphology image of the surface of the two-dimensional ferroelectric thin film prepared by this invention.

[0028] Figure 3 The results are ferroelectric fatigue test results of the photoelectric memristor based on van der Waals heterojunction prepared in Example 2 of this invention.

[0029] Figure 4 This is an 840-turn logarithmic I-V curve of the photoelectric memristor based on van der Waals heterojunction prepared in Example 2 of the present invention.

[0030] Figure 5 This is a logarithmic I-V curve of nine random units in the sample prepared in Example 2 of the present invention.

[0031] Figure 6This is a current response diagram of the photomemristor based on van der Waals heterojunction prepared in Embodiment 2 of the present invention under illumination of different wavelengths of light.

[0032] Figure 7 This is a stability diagram of the current response of the opto-memristor based on van der Waals heterojunction prepared in Example 2 of the present invention under illumination at a frequency of 1Hz and a wavelength of 808nm. Detailed Implementation

[0033] The following examples are provided to further illustrate the present invention, but they do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field and do not limit the invention in any way.

[0034] Example 1

[0035] like Figure 1 As shown, the opto-memristor based on van der Waals heterojunction provided by the present invention comprises, from bottom to top, a niobium-doped strontium titanate (Nb:SrTiO3, NSTO) conductive substrate layer, a Bi2Te... 3-x Se x / SnSe y A functional layer and a Pd top electrode layer are superimposed. Where 0 < x < 3, 0.6 < y < 2, Bi₂Te 3-x Se x / SnSe y The overlay functional layer is composed of SnSe y Functional layer and Bi2Te 3- x Se x Bi2Te is formed by stacking functional layers together. 3-x Se x The functional layer is located in SnSe y On the functional layer. Bi2Te 3-x Se x / SnSe y Stacking functional layers constitutes a van der Waals heterostructure.

[0036] Example 2

[0037] The method for fabricating a photoresistor based on a van der Waals heterojunction provided by this invention includes the following steps:

[0038] (1)SnSe yTarget preparation: Particulate Sn (99.999%) and Se (99.999%) were mixed in a Sn:Se ratio of 1:1.4 and calcined in a muffle furnace at 950°C for 24 hours. After cooling for 24 hours, the mixture was ball-milled, and then calcined in a plasma sintering furnace at 50 MPa and 525°C to obtain SnSe. 1.4 Target material.

[0039] (2)Bi2Te 3-x Se x Target preparation: Particulate Bi (99.999%), Te (99.999%), and Se (99.999%) were mixed in a Bi:Te:Se ratio of 2:2.7:0.3 and calcined in a muffle furnace at 950°C for 24 hours. After cooling for 24 hours, the mixture was ball-milled, and then the ball-milled bismuth tellurium selenide powder was calcined in a plasma sintering furnace at 50 MPa and 525°C to obtain Bi₂Te. 2.7 Se 0.3 Target material.

[0040] (3) Place the NSTO conductive substrate in a beaker containing acetone and clean it with ultrasonic waves for 10 minutes to further clean the oil stains on the surface of the NSTO conductive substrate. Then place the ultrasonically cleaned substrate in a beaker containing anhydrous ethanol and clean it with ultrasonic waves for 10 minutes to remove the residual acetone on the NSTO conductive substrate. Then take it out with tweezers and place it in a beaker containing deionized water and clean it with ultrasonic waves for 5 minutes to remove the anhydrous ethanol. Then take it out and dry it with N2.

[0041] (4) Preparation of the superimposed functional layer: First, polish the substrate sample stage in the pulsed laser deposition equipment cavity with sandpaper in a circular motion, then clean the organic impurities with acetone, then clean the residual acetone with anhydrous ethanol, and finally dry the sample stage surface with a nitrogen gun. Fix the substrate treated in step (3) to the sample stage with silver paste to prevent it from falling off during the experiment. Install the prepared sample stage into the heating stage in the pulsed laser deposition equipment cavity. 1.4 Target material and Bi2Te 2.7 Se 0.3 The target is fixed in the target holder, the appropriate target spacing is adjusted, and the cavity is evacuated to a back-bottom vacuum of 2×10⁻⁶. -4 Below Pa, heat the sample stage to 300℃ and maintain it for 10–15 minutes to ensure uniform heating. Introduce argon gas into the cavity and adjust the gate valve to maintain the pressure inside the cavity at 0.1 Pa. Turn on the excimer laser and adjust the laser energy density to 1.5 J / cm². 2 The laser frequency is 5Hz, so that the laser passes through the lens and hits SnSe. 1.4Pre-sputtering for 1 minute at the target center; followed by formal sputtering for 30 minutes to form an 8 nm thick SnSe layer on the NSTO conductive substrate. 1.4 Functional layer. Re-evacuate the cavity to a back-bottom vacuum of 2×10⁻⁶. -4 When the pressure is below 40 Pa, argon gas is introduced into the cavity, and the gate valve is adjusted to maintain the pressure in the cavity at 40 Pa. Then, Bi2Te gas is replaced. 2.7 Se 0.3 Set the target material, turn on the excimer laser, and adjust the laser energy density to 1.2 J / cm². 2 The laser frequency is 5Hz, so that the laser passes through a lens and hits Bi2Te. 2.7 Se 0.3 Pre-sputtering at the target center for 1 minute; followed by formal sputtering for 5 minutes on SnSe. 1.4 A 10nm thick Bi2Te layer was formed on the functional layer. 2.7 Se 0.3 Functional layer. Bi2Te 2.7 Se 0.3 Functional layer and SnSe 1.4 Functional layer formation Bi2Te 2.7 Se 0.3 / SnSe 1.4 The superimposed functional layer, namely Bi2Te 2.7 Se 0.3 Functional layer and SnSe 1.4 The van der Waals heterojunction structure formed by the functional layer.

[0042] (5) Use ultrasonic cleaning to clean the mask, acetone to clean the organic matter adhering to the mask surface, and finally wipe it clean with alcohol. Then, proceed with the growth of the Bi2Te mask. 2.7 Se 0.3 / SnSe 1.4 A photomask with 100-micrometer diameter circular holes was attached to the superimposed functional layer. The Bi₂Te₂ was then sputtered using a magnetron sputtering process. 2.7 Se 0.3 / SnSe 1.4 The electrode layer is sputtered onto the functional layer. After sputtering, the area of ​​the circular hole after the electrode layer is completed determines the effective working area of ​​this memristor. Using a DC magnetron sputtering system, remove the sample stage and target sleeve. Clean the surface impurities with sandpaper, wipe off any organic matter with acetone, and finally clean with alcohol. Fix the palladium target on the DC sputtering target stage, install the target sleeve, and evacuate the cavity to 1.8 × 10⁻⁶. -4 Argon gas was introduced into the chamber at 1 Pa, and the inlet valve was adjusted to maintain the pressure in the chamber at 1 Pa. The DC source controlling the ignition of the palladium target was turned on, and the power of the DC source was adjusted to 10 W to ignite the palladium target. Pre-sputtering was performed for 1 min; then formal sputtering was performed for 15 min on Bi2Te. 2.7 Se0.3 / SnSe 1.4 A 30nm thick Pd top electrode layer is generated on the superimposed functional layer. The Pd top electrode layer corresponds to the unmasked circular pattern with a diameter of 100 micrometers on the mask.

[0043] Performance testing

[0044] The Bi2Te prepared in Example 2 2.7 Se 0.3 / SnSe 1.4 The morphology of the stacked functional layers was characterized using atomic force microscopy (AFM). The morphology images of the sample scanned over a 5 μm × 5 μm area are shown below. Figure 2 As shown. By Figure 2 It can be seen that the Bi2Te prepared in Example 2 2.7 Se 0.3 / SnSe 1.4 The superimposed functional layer has good film surface smoothness, with a root mean square roughness of 2.31 nm.

[0045] The remanent polarization durability of the van der Waals heterojunction opto-memristor prepared in Example 2 was tested using a ferroelectric tester, and the results are as follows: Figure 3 As shown. Figure 3 As shown in the solid box, this structural device is subjected to an application of more than 10 9 Following a triangular wave voltage signal with an amplitude of ±1V and a period of 0.03ms, the positive residual polarization value remains at 5μC / cm. 2 The line connecting the circles in the figure shows that the negative remanent polarization value is stable at 2 μC / cm. 2 about.

[0046] The current-voltage characteristic curves of the van der Waals heterojunction photomemristor prepared in Example 2 were measured by applying a scanning voltage. The results are shown in [Figure 1]. Figure 4 The applied voltage was 0→3.3V→0→-3.5V→0. When a voltage of 0→3.3V→0 was applied, the resistance changed from a high resistance state (HRS) to a low resistance state (LRS); when a reverse voltage of 0→-3.5V→0 was applied, the resistance changed from a low resistance state (LRS) to a high resistance state (HRS). The 840-cycle IV curve test results showed good repeatability. Figure 5 Nine top electrodes at different locations were randomly selected from the sample prepared in Example 2, and their current-voltage characteristic curves were tested. It can be seen that under the same applied voltage, the current response ranges corresponding to the nine different top electrode locations are not significantly different, and all IV curves exhibit good switching behavior. Due to space limitations, we only provide the IV of nine randomly selected units here, with a yield of 80%–97%.

[0047] This invention also investigated the photoresponse characteristics of the van der Waals heterojunction photomemristor prepared in Example 2. Different wavelengths of light were irradiated onto the device without applying a bias voltage, such as... Figure 6 As shown, the wavelengths of the light sources used are 405nm, 450nm, 520nm, 650nm, and 808nm, with a frequency of 1Hz and an irradiance of 555mW / cm². 2 It was observed that after applying illumination, the device current decreased to -7.2 μA, -5 μA, -2.9 μA, -1.5 μA, and -0.3 μA, respectively, while the current rapidly increased to 0 when the illumination was removed. These results indicate that the fabricated van der Waals heterojunction photomemristor possesses stable photoelectric response characteristics, responding to both visible and near-infrared light regions. Furthermore, under the same optical power, the current intensity variation increases with decreasing wavelength.

[0048] Figure 7 The van der Waals heterojunction photomemristor prepared in Example 2 operates at a wavelength of 808 nm, a frequency of 1 Hz, and an irradiance of 555 mW / cm². 2 The stable characteristics of the current response under illumination. For example... Figure 7 As shown, the device current is 0 when there is no light, while when illuminated, the current response of the device is around -0.34μA and can be stabilized for more than 22,500 cycles.

[0049] The structure of the photoresist based on van der Waals heterojunction prepared in this invention can be represented as Pd / Bi2Te 3-x Se x / SnSe y / NbSrTiO3 is a non-volatile memory with excellent storage performance, good stability in the infrared band, high sample yield, and the ability to simultaneously achieve efficient storage and processing of information, making it a promising candidate for a wide range of applications.

Claims

1. A photoelectric memristor based on a van der Waals heterojunction, characterized in that, Its structure, from bottom to top, includes: a niobium-doped strontium titanate conductive substrate layer, a Bi2Te layer, and a strontium titanate conductive substrate layer. 3-x Se x / SnSe y Superimposed functional layer and Pd top electrode layer; wherein, 0 < x < 3, 0.6 < y < 2; Bi2Te 3-x Se x / SnSe y The overlay functional layer is composed of SnSe y Functional layer and Bi2Te 3-x Se x Bi2Te is formed by stacking functional layers together. 3-x Se x The functional layer is located in SnSe y On the functional layer; Bi2Te 3-x Se x / SnSe y Stacking functional layers constitutes a van der Waals heterostructure.

2. The opto-memristor based on a van der Waals heterojunction according to claim 1, characterized in that Sn Se y The functional layer thickness is 8–16 nm, Bi2Te 3-x Se x The thickness of the functional layer is 10–30 nm, and the thickness of the Pd top electrode layer is 30–60 nm.

3. The opto-memristor based on a van der Waals heterojunction according to claim 1, characterized in that, The Pd top electrode layer comprises several uniformly distributed layers in Bi2Te. 3－x Se x / SnSe y Circular electrodes on a superimposed functional layer.

4. A method for fabricating a photoelectric memristor based on a van der Waals heterojunction, characterized in that, Includes the following steps: (1) Preparation of SnSe y Target material: Particulate Sn and Se are mixed in a set ratio, calcined in a muffle furnace, cooled, ball-milled, and then the ball-milled tin selenide powder is calcined in a plasma sintering furnace to obtain SnSe. y Target material; (2) Preparation of Bi2Te 3-x Se x Target material: Particulate Bi, Te, and Se are mixed in a predetermined ratio, calcined in a muffle furnace, cooled, ball-milled, and then the ball-milled bismuth tellurium selenide powder is calcined in a plasma sintering furnace to obtain Bi2Te. 3-x Se x Target material; (3) The niobium-doped strontium titanate conductive substrate was ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water, and then dried with nitrogen. (4) Preparation of Bi2Te 3-x Se x / SnSe y Superimposed functional layer: SnSe is formed on a niobium-doped strontium titanate conductive substrate using pulsed laser deposition. y Functional layer, then in SnSe y Bi2Te is formed on the functional layer 3-x Se x Functional layer; SnSe y Functional layer and Bi2Te 3-x Se x Functional layers are stacked together to form Bi2Te 3-x Se x / SnSe y Superimposed functional layers; where 0 < x < 3, 0.6 < y < 2; (5) Preparation of Pd top electrode layer: In Bi2Te 3-x Se x / SnSe y A photomask with 100-micrometer diameter circular holes is attached to the superimposed functional layer. The Bi2Te layer is then deposited using magnetron sputtering. 3-x Se x / SnSe y A Pd top electrode layer is formed by sputtering on the superimposed functional layer.

5. The method for fabricating a photoresistor based on a van der Waals heterojunction according to claim 4, characterized in that, In step (1), the ratio of granular Sn and Se is Sn:Se = 1:1 to 1:

5. Sn and Se are calcined in a muffle furnace at 600 to 950°C for 24 hours, then cooled for 24 hours, ball-milled, and then the ball-milled tin selenide powder is calcined again in a plasma sintering furnace at 40 to 50 MPa and 400 to 525°C.

6. The method for fabricating a photoelectric memristor based on a van der Waals heterojunction according to claim 4, characterized in that, In step (2), the ratio of granular Bi, Te and Se is set as Bi:Te:Se = 2:3 - x:x; where 0 < x < 3; Bi, Te and Se are calcined in a muffle furnace at 600-950℃ for 24h, then cooled for 24h, ball-milled, and the ball-milled bismuth tellurium selenide powder is calcined again in a plasma sintering furnace at 40-50MPa and 400-525℃.

7. The method for fabricating a photoresistor based on a van der Waals heterojunction according to claim 4, characterized in that, In step (4), SnSe is prepared. y For the functional layer, the parameters of the pulsed laser deposition process are as follows: argon gas is introduced into the cavity to maintain a pressure of 0.1–3 Pa, and the laser energy density is 1.5–3 J / cm². 2 The laser frequency is 1–5 Hz, and the substrate temperature is 50–500 °C; Bi₂Te is prepared. 3-x Se x For the functional layer, the parameters for pulsed laser deposition are as follows: argon gas is introduced into the cavity to maintain a pressure of 10–40 Pa, and the laser energy density is 1.2–3 J / cm². 2 The laser frequency is 1-5 Hz, and the substrate temperature is 50-500℃.

8. The method for fabricating a photoresistor based on a van der Waals heterojunction according to claim 4, characterized in that, In step (5), when preparing the Pd top electrode layer, the parameters of the magnetron sputtering process are as follows: the cavity is evacuated to 1.8 × 10⁻⁶. -4 Pa, argon gas is introduced into the cavity, and the pressure in the cavity is adjusted to maintain 0.1-20 Pa. The DC source controlling the palladium target ignition is turned on, and the power of the DC source is adjusted to 5-20 W to make the palladium target ignite. Pre-sputter for 1 min, and then perform formal sputtering for 15 min.

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