Linear polarization direction identification method and photoelectric detector

Abstract

The invention belongs to the field of optoelectronic devices, and particularly relates to a linear polarization direction identification method and a photoelectric detector, and the method comprises the steps: to-be-detected linear polarization light is emitted to a nanosheet structure formed by sequentially stacking a first 1T 'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T' MoTe2 nanosheet, and the three layers of nanosheets are partially overlapped; an electrode is arranged on each of the two 1T 'MoTe2 nanosheets; two electrodes are arranged on the MoS2 nanosheet; the included angle between the molybdenum chain directions of the two 1T 'MoTe2 nanosheets is not 0 degree and 90 degrees, the vertically stacked 1T' MoTe2 / MoS2 / 1T 'MoTe2 heterojunctions are used, the polarization sensitivity of the 1T' MoTe2 is utilized, two bias voltages in opposite directions are applied, the voltage is applied and the current is collected by the electrodes, and the polarization direction of incident polarized light is deduced. The on-chip integrated polarization angle identification can be realized.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic devices, and more specifically, relates to a linear polarization direction identification method and a photoelectric detector. Background Art

[0002] As a major branch of sensing technology, photoelectric detection technology has shown great application value in national defense and people's livelihood. In particular, polarization detection can obtain light polarization vector information, light intensity, spectrum, polarization direction and other information, and has significant advantages in suppressing environmental interference, increasing detection distance, obtaining target details, and identifying camouflaged targets. Therefore, it is widely used in military equipment, aerospace remote sensing, industrial production, medical diagnosis and other fields.

[0003] The current linear polarization direction recognition photodetector is mainly based on the amplitude-divided photodetector integrated with the metal grating and the ordinary photodetector. The material itself is not sensitive to polarized light, but relies on the metal grating so that the light with the polarization direction parallel to the grating can pass through the grating and be absorbed by the material, which seriously limits the detection rate of the device. In recent years, polarization light detectors based on in-plane anisotropic two-dimensional materials have attracted people's attention. Although anisotropic two-dimensional materials are sensitive to the polarization direction of polarized light, they cannot determine the light intensity and polarization direction.

[0004] For a beam of linearly polarized light of unknown intensity and polarization direction, the response of the polarization photodetector is a structure in which light intensity and polarization direction work together. When the polarization direction of light is symmetrical to the optical principal axis of the anisotropic two-dimensional material, the light response of a single anisotropic two-dimensional material polarization detector is the same. The polarization direction of light cannot be determined by relying on a single anisotropic two-dimensional material.

[0005] Therefore, the current device structure still needs to be improved and developed. Summary of the invention

[0006] In view of the defects and improvement needs of the prior art, the present invention provides a linear polarization direction recognition method and a photoelectric detector, which aims to achieve on-chip integrated linear polarization direction recognition.

[0007] To achieve the above object, according to one aspect of the present invention, a method for identifying a linear polarization direction is provided, comprising:

[0008] The linearly polarized light to be measured is directed to a nanosheet structure composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet stacked in sequence, wherein the three layers of nanosheets partially overlap; an electrode is provided on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are provided on the MoS2 nanosheet to form a second electrode pair; and the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°.

[0009] After applying a preset voltage to the second electrode pair, the first photocurrent between the second electrode pair is collected, and the light intensity of the linear polarized light is obtained according to the corresponding photocurrent-light intensity relationship under the preset voltage that is calibrated in advance; a forward bias is applied to the first electrode pair, and the second photocurrent between the first electrode pair is collected, and two candidate polarization directions of the linear polarized light to be measured are determined according to the relationship between the second photocurrent and the polarization direction under the light intensity that is calibrated in advance; a negative bias is applied to the first electrode pair, and the third photocurrent between the first electrode pair is collected, and the other two candidate polarization directions of the linear polarized light to be measured are determined according to the relationship between the third photocurrent and the polarization direction under the light intensity that is calibrated in advance; two identical polarization directions among the four candidate polarization directions are the polarization directions of the linear polarized light to be measured, and the identification is completed.

[0010] Furthermore, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is between 5° and 85°.

[0011] Furthermore, the angle between the Mo chain directions of two 1T'MoTe2 nanosheets is 45°.

[0012] The present invention also provides a linear polarization direction recognition photoelectric detector, comprising: a nanosheet structure formed by sequentially stacking a first 1T'MoTe2 nanosheet, a MoS2 nanosheet, and a second 1T'MoTe2 nanosheet;

[0013] Among them, the three layers of nanosheets partially overlap; one electrode is set on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are set on the MoS2 nanosheet to form a second electrode pair; the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°.

[0014] Further, it also includes an identification control module;

[0015] The identification control module is connected to the first electrode pair and the second electrode pair, and is used to perform the direction identification operation steps in the linear polarization direction identification method as described above.

[0016] Furthermore, the thickness of the two layers of 1T'MoTe2 nanosheets is in the range of 3nm to 100nm, and the thickness of the MoS2 nanosheets is in the range of 3nm to 100nm.

[0017] Furthermore, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is between 5° and 85°.

[0018] Furthermore, the angle between the Mo chain directions of two 1T'MoTe2 nanosheets is 45°.

[0019] The present invention also provides a method for preparing the linear polarization direction recognition photoelectric detector as described above, comprising:

[0020] 1T'MoTe2 nanosheets and MoS2 nanosheets of desired shapes and thicknesses are obtained on substrates by mechanical exfoliation or chemical vapor deposition.

[0021] The nanosheets are transferred using PMMA-assisted wet transfer, PVA-assisted wet transfer or PDMS dry transfer methods. First, one of the 1T'MoTe2 nanosheets is transferred to the target area of ​​the substrate, and then a MoS2 nanosheet is covered on the 1T'MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction. Then another 1T'MoTe2 nanosheet is covered on the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 vertical heterojunction, wherein the bottom 1T'MoTe2 nanosheet, MoS2 nanosheet and top 1T'MoTe2 nanosheet in the vertical heterojunction partially overlap.

[0022] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0023] (1) The present invention proposes to direct the linearly polarized light to be measured toward a nanosheet structure which is composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet stacked in sequence, wherein the three layers of nanosheets partially overlap; an electrode is provided on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are provided on the MoS2 nanosheet to form a second electrode pair; the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°, that is, the detection structure proposed by the present invention is simple and the required preparation process is simple; further, after applying a preset voltage to the second electrode pair, a first photocurrent between the second electrode pair is collected, and the light intensity of the linearly polarized light is obtained according to the photocurrent-light intensity relationship corresponding to the preset voltage which is pre-calibrated; the first electrode pair is directed to the first electrode pair A forward bias is applied to the electrode pair, and the second photocurrent between the first electrode pair is collected. According to the relationship between the second photocurrent and the polarization direction under the pre-calibrated light intensity, two candidate polarization directions of the linear polarized light to be measured are determined; a negative bias is applied to the first electrode pair, and the third photocurrent between the first electrode pair is collected. According to the relationship between the third photocurrent and the polarization direction under the pre-calibrated light intensity, the other two candidate polarization directions of the linear polarized light to be measured are determined; the two identical polarization directions among the four candidate polarization directions are the polarization directions of the linear polarized light to be measured, and the identification is completed. That is, using the vertically stacked 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction, with the help of the polarization sensitivity of 1T'MoTe2 itself, the polarization direction of the incident polarized light can be inferred by applying two biases in opposite directions. It is possible to achieve on-chip integrated polarization angle identification without using a polarizer or half-wave plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram corresponding to a method for identifying a linear polarization direction provided by an embodiment of the present invention;

[0025] Figure 2 A structural diagram of a linear polarization direction recognition photoelectric detector provided by an embodiment of the present invention;

[0026] Figure 3 A physical picture of a linear polarization direction recognition photoelectric detector provided in an embodiment of the present invention;

[0027] Figure 4 A rectangular coordinate diagram of the 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction polarization state recognition photodetector provided in an embodiment of the present invention for recognizing the polarization state of incident light according to the light current under positive bias and the light current under negative bias.

[0028] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0029] 1 and 2 are two layers of materials on the substrate, 3 is a MoS2 nanosheet, 4 and 5 are two electrodes in the second electrode pair, 6 is the first 1T'MoTe2 nanosheet, 7 and 9 are two electrodes in the first electrode pair, and 8 is the second 1T'MoTe2 nanosheet. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Embodiment 1

[0032] A method for identifying a linear polarization direction, comprising:

[0033] The linearly polarized light to be measured is directed to a nanosheet structure composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet stacked in sequence, wherein the three layers of nanosheets partially overlap, and the overlapping parts constitute a vertical heterojunction; an electrode is provided on each of the two 1T'MoTe2 nanosheets to constitute a first electrode pair; two electrodes are provided on the MoS2 nanosheet to constitute a second electrode pair; and the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°.

[0034] After applying a preset voltage to the second electrode pair, a first photocurrent between the second electrode pair is collected, and the light intensity of the linearly polarized light is obtained according to the photocurrent-light intensity relationship corresponding to the preset voltage that is calibrated in advance; a forward bias is applied to the first electrode pair, and a second photocurrent between the first electrode pair is collected, and according to the relationship between the second photocurrent and the polarization direction under the light intensity that is calibrated in advance, as shown in FIG. Figure 1 As shown, two candidate polarization directions of the linear polarized light to be measured are determined; a negative bias is applied to the first electrode pair, and a third photocurrent between the first electrode pair is collected. According to the relationship between the third photocurrent and the polarization direction under the pre-calibrated light intensity, as shown in FIG. Figure 1 As shown, the other two candidate polarization directions of the linear polarized light to be measured are determined; the two identical polarization directions among the four candidate polarization directions are the polarization directions of the linear polarized light to be measured, and the identification is completed.

[0035] It should be noted that Figure 1 The specific data shown corresponds to the light current-angle polar coordinate diagram of the 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction polarization state recognition photodetector under 915nm incident light and positive bias / negative bias.

[0036] In this embodiment, 1T'MoTe2 is used as a polarization-direction-sensitive material in a Schottky heterojunction, and it has intrinsic in-plane anisotropy, and the polarization information of light can be determined based on the photocurrent of the Schottky heterojunction, without the need for an additional polarizer. Furthermore, the contact portions between the first 1T'MoTe2 and MoS2, and between the second 1T'MoTe2 and MoS2 respectively construct polarization-sensitive 1T'MoTe2 / MoS2 Schottky heterojunctions, which can effectively promote the separation of photogenerated carriers and realize the conversion of photoelectric signals; in addition, the photocurrent of the device is affected by both light intensity and polarization direction. If the polarization direction of polarized light is to be identified, the incident light intensity must be determined first. When the polarization direction of light is symmetrical with respect to the maximum light response direction of the 1T'MoTe2 / MoS2 Schottky heterojunction, the photocurrent generated in the heterojunction is the same, so the polarization direction of polarized light cannot be determined by relying solely on a 1T'MoTe2 / MoS2 Schottky junction device. In the 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction proposed in this embodiment, there is a certain angle between the directions of the molybdenum chains of the two layers of 1T'MoTe2, which causes a certain angle between the two Schottky heterojunctions in the maximum light response direction of polarized light. When performing polarization state identification, the intensity of the polarized light is determined by using the photocurrent between the second electrode pair in the non-overlapping area of ​​MoS2; then the polarization direction of the polarized light is tested by using the photocurrent of the first electrode pair in the non-overlapping area of ​​the two 1T'MoTe2 nanosheets, specifically including: firstly applying a certain forward bias voltage to the first electrode pair to suppress the built-in electric field between one 1T'MoTe2 nanosheet and the MoS2 nanosheet applied by the positive pressure, enhancing the built-in electric field between the other 1T'MoTe2 nanosheet and the MoS2 nanosheet, and recording the photocurrent at this time. According to the photocurrent of the light intensity at this time, the linear polarized light relative to the above-mentioned other one can be obtained. The two possible polarization directions of the molybdenum chain direction of the nanosheets are then changed to a negative bias on the first electrode pair to suppress the built-in electric field between one 1T'MoTe2 nanosheet and the MoS2 nanosheet applied by the negative pressure, and enhance the built-in electric field between the other 1T'MoTe2 nanosheet and the MoS2 nanosheet. The photocurrent at this time is recorded, and the two possible polarization directions of the linear polarized light relative to the other one can be obtained based on the photocurrent of the light intensity at this time. When the angle between the molybdenum chain directions of the two layers of 1T'MoTe2 is not 0° or 90°, one pair of these four polarization directions will overlap, which is the actual polarization direction of the polarized light.

[0037] As a preferred embodiment, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is between 5° and 85°. Preferably, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is 45°.

[0038] The fitting relationship between the photocurrent and the linear polarization angle under the positive bias between the first electrode pair can be expressed as I ph1 =A1cos(2(θ+φ1))+B1, the fitting relationship between the photocurrent and the linear polarization angle under negative bias can be expressed as I ph2 =A2cos(2(θ+φ2))+B2,I ph1 with I ph2 The phase difference Δφ between them is equal to the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets. Since the inverse trigonometric function is required to calculate the polarization angle based on the photocurrent, and a slight fluctuation in the current near the photocurrent extreme value will cause a large error in the angle calculation, when the angle between the two is 45 degrees, I ph1 with I ph2 The extreme phase difference is 45 degrees, which is conducive to more accurate angle calculation.

[0039] Embodiment 2

[0040] A linear polarization direction recognition photodetector, such as Figure 2 As shown, Figure 2 The upper figure is a top view, and the lower figure is a cross-sectional view, including: a nanosheet structure composed of a first 1T'MoTe2 nanosheet 6, a MoS2 nanosheet 3, and a second 1T'MoTe2 nanosheet 8 stacked in sequence;

[0041] Among them, the three layers of nanosheets are partially overlapped; each of the two 1T'MoTe2 nanosheets is provided with an electrode 7, 9, forming a first electrode pair; the MoS2 nanosheet is provided with two electrodes 4, 5, forming a second electrode pair; the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°. Figure 2 1 and 2 are two layers of material on the substrate. Figure 3 This is a real picture.

[0042] As a preferred embodiment, it further includes an identification control module; wherein the identification control module is connected to the first electrode pair and the second electrode pair, and is used to perform the direction identification operation steps in the linear polarization direction identification method as described in Example 1. That is, in Example 1, the identification step after the linear polarized light is emitted to the nanosheet structure can be automatically implemented by the identification control module.

[0043] As a preferred embodiment, the thickness of the two layers of 1T'MoTe2 nanosheets is in the range of 3nm to 100nm, and the thickness of the MoS2 nanosheet is in the range of 3nm to 100nm. The thickness of the middle layer MoS2 nanosheet is small, and the middle layer can be completely ionized during the direction recognition process, which will make the device response speed and detection rate higher.

[0044] As a preferred embodiment, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is between 5° and 85°. Preferably, the angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is 45°.

[0045] As an implementation method, the material of the first electrode pair and the second electrode pair may be Ti, Cr, Au, Ag, Al, etc., and the thickness of the first electrode pair and the second electrode pair is between 50-200 nm.

[0046] Embodiment 3

[0047] A method for preparing the linear polarization direction recognition photoelectric detector as described above comprises:

[0048] providing a substrate;

[0049] 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets are provided respectively, wherein the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets are sequentially located above the substrate, and the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets partially overlap to form a vertical heterojunction,

[0050] A first electrode pair and a second electrode pair are formed, wherein the first electrode of the first electrode pair is arranged on the unstacked area between the substrate and the lower 1T'MoTe2 nanosheet, and the second electrode of the first electrode pair is arranged on the unstacked area between the substrate and the upper 1T'MoTe2 nanosheet; and the second electrode pair is arranged on the unstacked area between the substrate and the middle MoS2 nanosheet.

[0051] As an implementation method, 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets are provided respectively, and the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets are sequentially located above the substrate, and the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets partially overlap to form a vertical heterojunction, including the following steps:

[0052] On the substrate, a mechanical exfoliation method or a chemical vapor deposition method is used to obtain MoTe2 nanosheets and MoS2 nanosheets of suitable shape and thickness respectively;

[0053] The nanosheets are transferred using PMMA-assisted wet transfer, PVA-assisted wet transfer or PDMS dry transfer methods. First, the bottom layer 1T'MoTe2 nanosheets are transferred to the target area of ​​the substrate, and then the MoS2 nanosheets are covered on the MoTe2 nanosheets to form a 1T'MoTe2 / MoS2 heterojunction. Then, the top layer 1T'MoTe2 nanosheets are covered on the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 vertical heterojunction, wherein the bottom layer 1T'MoTe2 nanosheets, MoS2 nanosheets and top layer 1T'MoTe2 nanosheets of the vertical heterojunction partially overlap.

[0054] The structure of the present invention or the structure prepared based on the exemplary method focuses on forming a 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction. The polarization state recognition photodetector uses 1T'MoTe2 nanosheets, MoS2 nanosheets, and 1T'MoTe2 nanosheets as heterojunctions to form a Schottky heterojunction with two directions of energy, which can achieve rapid response of the device and realize wide spectrum detection with the help of the semi-metallic properties of 1T'MoTe2.

[0055] The electrode setting is achieved through coating processes such as electron beam evaporation, thermal evaporation, magnetron sputtering, and atomic layer deposition.

[0056] In addition, after the device is prepared, annealing is performed under inert gas conditions, specifically: the annealing temperature is 200° C. to 400° C.; the annealing time is 1 to 3 hours.

[0057] In order to better illustrate this embodiment, the following preparation examples are given:

[0058] Example 1, the steps include:

[0059] Step 1: Select a 1 cm × 1 cm silicon oxide wafer with a 300 nm oxide layer as a substrate, wash it with acetone, ethanol, and deionized water in sequence, and then blow dry it for later use.

[0060] Step 2: Weigh 5 g of PVA and dissolve it in 95 ml of deionized water to obtain a 5% PVA solution. Spin coat the PVA solution on a glass plate at a speed of 500 r / min, and then dry it on a hot plate at 50 degrees to obtain a PVA film. Cut the PVA film into a size of 2 mm × 2 mm and stick it on a 5 mm × 5 mm PDMS film.

[0061] Step 3: Select a 20 nm thick long single-crystalline 1T'MoTe2 nanosheet prepared by mechanical exfoliation, pick up the 1T'MoTe2 nanosheet using the PVA / PDMS film prepared in step 2, and transfer it to the target substrate. Then heat the substrate to 60 degrees to make the PVA film carrying the 1T'MoTe2 nanosheet fit tightly to the substrate, remove the PDMS film, and then soak it in deionized water for 1 hour to remove the PVA.

[0062] Step 4, select a long strip of single-crystalline MoS2 nanosheet with a thickness of about 10 nm prepared by mechanical exfoliation, pick up the MoS2 nanosheet using the PVA / PDMS film prepared in step 2, align the long edge of the MoS2 nanosheet with the long edge of 1T'MoTe2 and cover it on the 1T'MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction, and then soak it in deionized water for 1 hour to remove PVA.

[0063] Step 5, select a long strip of single-crystal 1T'MoTe2 nanosheet with a thickness of 20 nm prepared by mechanical stripping, and use the PVA / PDMS film prepared in step 2 to pick up the 1T'MoTe2 nanosheet, so that the long side of the 1T'MoTe2 nanosheet is at an angle of 60 degrees with the long side of the 1T'MoTe2 on the substrate and covers the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction, and then soak it in deionized water for 1 hour to remove the PVA.

[0064] Step 6, prepare the first electrode pair and the second electrode pair. Spin-coat electron beam photoresist on the substrate with the heterojunction for electron beam lithography, and then perform development to complete the patterning of the electrode. Use electron beam evaporation to deposit 10nm Cr and 50nm Au, and then remove the resist to obtain the deposited electrode.

[0065] Step 7, annealing the device. The device is placed in a tube furnace for annealing. Argon gas is used for protection during the annealing process. The argon gas flow rate is 1 slm, the annealing temperature is 250 degrees, and the annealing time is 2 hours.

[0066] Example 2, the steps include:

[0067] Step 1: Select a quartz substrate of 1 cm×1 cm in size, wash it with acetone, ethanol, and deionized water in sequence, and then blow dry it for later use.

[0068] Step 2: Select a 5 mm × 5 mm PDMS film to be used as a stamp for transferring nanosheets.

[0069] Step 3: Select a CVD-grown single-crystal 1T'MoTe2 nanosheet with a thickness of 20 nm, find the x-axis direction of the nanosheet, etch the nanosheet into long strips, pick up the 1T'MoTe2 nanosheet using a PDMS film, and transfer it to the target substrate. Then heat the substrate to 80 degrees and keep it for 20 minutes until the PDMS loses its viscosity. Then remove the PDMS film to keep the 1T'MoTe2 nanosheet on the substrate.

[0070] Step 4, select a single crystal MoS2 nanosheet with a thickness of about 10 nm grown by CVD, etch the nanosheet into long strips, pick up the MoS2 nanosheet using a PDMS film, align the long side of the MoS2 nanosheet with the long side of 1T'MoTe2 and cover it on the 1T'MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction, then heat the substrate to 80 degrees, keep it for 20 minutes until the PDMS loses its viscosity, and remove the PDMS film.

[0071] Step 5, select a CVD-grown single-crystal 1T'MoTe2 nanosheet with a thickness of 20 nm, find the x-axis direction of the nanosheet, etch the nanosheet into long strips, use a PDMS film to pick up the 1T'MoTe2 nanosheet, make the angle between the long side of the 1T'MoTe2 nanosheet and the long side of the 1T'MoTe2 on the substrate be 45 degrees, and cover the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction, then heat the substrate to 80 degrees, keep it for 20 minutes until the PDMS loses its viscosity, and remove the PDMS film.

[0072] Step 6, prepare the first electrode pair and the second electrode pair. Perform maskless laser direct writing photolithography on the photoresist on the substrate with the heterojunction, and then complete the patterning of the electrode by development. Use thermal evaporation to deposit 10nm Ti and 100nm Au, and then remove the resist to obtain the deposited electrode.

[0073] Step 7, annealing the device. The device is placed in a tube furnace for annealing. During the annealing process, an argon-hydrogen mixed gas with a hydrogen concentration of 5% is used for protection, the flow rate is 1 slm, the annealing temperature is 300 degrees, and the annealing time is 1.5 hours.

[0074] In general, the present invention solves the problem of polarization direction identification in current linear polarization detection. Current polarization light detectors are mainly divided into time-sharing polarization photodetectors and focal plane polarization photodetectors. They have complex preparation processes, require the use of polarizers or half-wave plates, resulting in bulky equipment, and cannot detect in real time. The present invention uses a vertically stacked 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction. With the help of the polarization sensitivity of 1T'MoTe2 itself, the polarization direction of the incident polarized light can be inferred by applying two bias voltages in opposite directions. It can realize on-chip integrated polarization angle identification without the use of polarizers or half-wave plates. Reduce the detection volume and achieve on-chip integration.

[0075] It will be easily understood by those skilled in the art that 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.

Claims

1. A method for identifying a linear polarization direction, characterized in that: include: The linear polarized light to be measured is directed to a nanosheet structure composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet stacked in sequence, wherein the three nanosheets partially overlap; an electrode is disposed on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are disposed on the MoS2 nanosheet to form a second electrode pair; and the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° or 90°; After applying a preset voltage to the second electrode pair, a first photocurrent between the second electrode pair is collected, and the light intensity of the linearly polarized light is obtained according to a pre-calibrated photocurrent-light intensity relationship corresponding to the preset voltage; A forward bias is applied to the first electrode pair, and a second photocurrent between the first electrode pair is collected. Based on the relationship between the second photocurrent and the polarization direction under the light intensity that is calibrated in advance, two candidate polarization directions of the linear polarized light to be measured are determined. A negative bias is applied to the first electrode pair, and a third photocurrent between the first electrode pair is collected. Based on the relationship between the third photocurrent and the polarization direction under the light intensity that is calibrated in advance, another two candidate polarization directions of the linear polarized light to be measured are determined. Two identical polarization directions among the four candidate polarization directions are the polarization directions of the linear polarized light to be measured, and identification is completed.

2. A method for identifying a linear polarization direction according to claim 1, characterized in that: The angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets ranges from 5° to 85°.

3. A method for identifying a linear polarization direction according to claim 2, characterized in that: The angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is 45°.

4. A linear polarization direction recognition photoelectric detector, characterized in that: include: A nanosheet structure composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet stacked in sequence; Among them, the three layers of nanosheets partially overlap; one electrode is set on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are set on the MoS2 nanosheet to form a second electrode pair; the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° and 90°.

5. The linear polarization direction recognition photoelectric detector according to claim 4, characterized in that: Also included is an identification control module; The identification control module is connected to the first electrode pair and the second electrode pair, and is used to perform the direction identification operation steps in the linear polarization direction identification method according to claim 1.

6. The linear polarization direction recognition photoelectric detector according to claim 4, characterized in that: The thickness of the two layers of 1T'MoTe2 nanosheets ranges from 3nm to 100nm, and the thickness of the MoS2 nanosheets ranges from 3nm to 100nm.

7. The linear polarization direction recognition photoelectric detector according to claim 4, characterized in that: The angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets ranges from 5° to 85°.

8. The linear polarization direction recognition photoelectric detector according to claim 4, characterized in that: The angle between the molybdenum chain directions of two 1T'MoTe2 nanosheets is 45°.

9. A method for preparing a linear polarization direction recognition photoelectric detector according to any one of claims 4 to 8, characterized in that: include: 1T'MoTe2 nanosheets and MoS2 nanosheets of desired shapes and thicknesses are obtained on substrates by mechanical exfoliation or chemical vapor deposition. The nanosheets are transferred using PMMA-assisted wet transfer, PVA-assisted wet transfer or PDMS dry transfer methods. First, one of the 1T'MoTe2 nanosheets is transferred to the target area of ​​the substrate, and then a MoS2 nanosheet is covered on the 1T'MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction. Then another 1T'MoTe2 nanosheet is covered on the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 vertical heterojunction, wherein the bottom 1T'MoTe2 nanosheet, MoS2 nanosheet and top 1T'MoTe2 nanosheet in the vertical heterojunction partially overlap.

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