Linear polarization direction identification method and photoelectric detector

Abstract

The application belongs to the field of optoelectronic devices, and particularly relates to a linear polarization direction identification method and a photoelectric detector. The method comprises the steps of: irradiating a linear polarization light to be detected to a nanosheet structure composed of a first 1T'MoTe2 nanosheet, a MoS2 nanosheet and a second 1T'MoTe2 nanosheet which are stacked in sequence, and the three nanosheets are partially overlapped; an electrode is arranged on each of the two 1T'MoTe2 nanosheets; two electrodes are arranged on the MoS2 nanosheet; and the included angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° or 90°. The vertically stacked 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction is used, the polarization sensitivity of the 1T'MoTe2 itself is utilized, opposite bias in two directions is applied, and the polarization direction of the incident polarized light is inferred by means of the voltage applied by the electrode and the current collected. The application can realize on-chip integrated polarization angle identification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optoelectronic devices, and more particularly relates to a linear polarization direction identification method and a photodetector. BACKGROUND

[0002] As a branch of sensing technology, photodetection technology has shown great application value in national defense and people's livelihood. Especially, polarization detection can obtain light polarization vector information, obtain light intensity, spectrum, polarization direction and other information, and has significant advantages in suppressing environmental interference, improving detection distance, obtaining target detail characteristics, identifying camouflage targets and other aspects, and is widely used in military equipment, space remote sensing, industrial production, medical diagnosis and other fields.

[0003] The current linear polarization direction identification photodetector is mainly a split-amplitude photodetector based on the integration of a metal grating and a general photodetector. The material itself is not sensitive to polarized light, but relies on the metal grating to make the polarization direction parallel to the grating. The light can be transmitted through the grating and then absorbed by the material, which severely limits the detection rate of the device. In recent years, polarization light detectors based on in-plane anisotropic two-dimensional materials have attracted 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 linearly polarized light with unknown intensity and polarization direction, the response of the polarization photodetector is a structure that the light intensity and the polarization direction act together. When the polarization direction of the light is symmetrical to the optical principal axis of the anisotropic two-dimensional material, the light response of the single anisotropic two-dimensional material polarization detector is the same. Therefore, relying on a single anisotropic two-dimensional material cannot determine the polarization direction of the light.

[0005] Therefore, the current device structure needs to be improved and developed. SUMMARY

[0006] In view of the defects and improvement needs of the prior art, the present application provides a linear polarization direction identification method and a photodetector, which aims to realize on-chip integration of linear polarization direction identification.

[0007] To achieve the above-mentioned purpose, according to one aspect of the present application, a linear polarization direction identification method is provided, comprising:

[0008] The linearly polarized light to be measured is shot 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 are partially overlapped; an electrode is arranged on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are arranged on the MoS2 nanosheet to form a second electrode pair; and the included angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° or 90°.

[0009] After a preset voltage is applied 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, and two candidate polarization directions of the to-be-measured linearly polarized light are determined according to a pre-calibrated relationship between the second photocurrent and the polarization direction under the light intensity; a negative bias is applied to the first electrode pair, and a third photocurrent between the first electrode pair is collected, and another two candidate polarization directions of the to-be-measured linearly polarized light are determined according to a pre-calibrated relationship between the third photocurrent and the polarization direction under the light intensity; two same polarization directions in the four candidate polarization directions are the polarization direction of the to-be-measured linearly polarized light, and the identification is completed.

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

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

[0012] The application further provides a linear polarization direction identification photoelectric detector, comprising: a nanosheet structure composed of a first 1T' MoTe2 nanosheet, a MoS2 nanosheet and a second 1T' MoTe2 nanosheet stacked in sequence.

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

[0014] Further, it further comprises an identification control module;

[0015] Among them, the identification control module is connected with the first electrode pair and the second electrode pair, and is used for executing the direction identification operation steps in the linear polarization direction identification method.

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

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

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

[0019] The application further provides a preparation method of the linear polarization direction recognition photoelectric detector, comprising the following steps:

[0020] 1T'MoTe2 nanosheets and MoS2 nanosheets with required shapes and thicknesses are respectively obtained on a substrate by a mechanical exfoliation method or a chemical vapor deposition method;

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

[0022] Overall, the above technical solutions conceived by the application can achieve the following beneficial effects:

[0023] (1) the application proposes that the linearly polarized light to be measured is shot to the nanosheet structure composed of first 1T'MoTe2 nanosheet, MoS2 nanosheet and second 1T'MoTe2 nanosheet in turn, wherein the three-layer nanosheet is partially overlapped;An electrode is arranged on each of the two 1T'MoTe2 nanosheets to form a first electrode pair;Two electrodes are arranged on the MoS2 nanosheet to form a second electrode pair;The included 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 application is simple, and the required preparation process is simple;Further, after a preset voltage is applied to the second electrode pair, the first photocurrent between the second electrode pair is collected, the corresponding photocurrent-light intensity relationship under the preset voltage is calibrated in advance, and the light intensity of the linearly polarized light is obtained;A forward bias is applied to the first electrode pair, and the second photocurrent between the first electrode pair is collected, and the relationship between the second photocurrent and the polarization direction under the light intensity is calibrated in advance to determine the two candidate polarization directions of the linearly polarized light to be measured;A negative bias is applied to the first electrode pair, and the third photocurrent between the first electrode pair is collected, and the relationship between the third photocurrent and the polarization direction under the light intensity is calibrated in advance to determine the other two candidate polarization directions of the linearly polarized light to be measured;Two same polarization directions in the four candidate polarization directions are the polarization direction of the linearly polarized light to be measured, the recognition is completed, that is, the vertically stacked 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction is used, the polarization sensitivity of 1T'MoTe2 itself is used, and the polarization direction of the incident polarized light can be inferred by applying two opposite direction biases. It can realize on-chip integrated polarization angle recognition without using polarizer or half-wave plate. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A linear polarization direction recognition method corresponding to the principle diagram provided by the embodiment of the application;

[0025] Figure 2 A linear polarization direction recognition photoelectric detector structure diagram provided by the embodiment of the application;

[0026] Figure 3 A linear polarization direction recognition photoelectric detector provided by the embodiment of the application;

[0027] Figure 4 A 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction polarization state recognition photoelectric detector according to the right-angle coordinate diagram of recognizing the polarization state of incident light according to the light illumination current under positive bias and the light illumination current under negative bias.

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

[0029] 1, 2 are two layers of material on the substrate, 3 is MoS2 nanosheet, 4, 5 are two electrodes in the second electrode pair, 6 is the first 1T'MoTe2 nanosheet, 7, 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 scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1

[0032] A linear polarization direction recognition method, comprising:

[0033] The linearly polarized light to be measured is shot 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 part forms a vertical heterojunction; an electrode is arranged on each of the two 1T'MoTe2 nanosheets to form a first electrode pair; two electrodes are arranged on the MoS2 nanosheet to form a second electrode pair; and the included angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is not 0° or 90°.

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

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

[0036] In this embodiment, 1T'MoTe2 as a polarization direction sensitive material in the Schottky heterojunction has intrinsic in-plane anisotropy, and the polarization information of light can be judged according to the photocurrent of the Schottky heterojunction without using an additional polarizer. Further, the contact parts between the first 1T'MoTe2 and MoS2 and between the second 1T'MoTe2 and MoS2 respectively construct the 1T'MoTe2 / MoS2 Schottky heterojunction sensitive to polarized light, which can effectively promote the separation of photo-generated 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 the polarized light is to be identified, the incident light intensity must be determined first. When the polarization direction of the light is symmetrical to the maximum light response direction of the 1T'MoTe2 / MoS2 Schottky heterojunction, the photocurrent generated in the heterojunction is the same, so a single 1T'MoTe2 / MoS2 Schottky junction device cannot determine the polarization direction of the polarized light. In this embodiment, the molybdenum chain directions of the two layers of 1T'MoTe2 in the 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction have a certain angle, which makes the maximum light response directions of the two Schottky heterojunctions to the polarized light have a certain angle. When identifying the polarization state, the photocurrent between the second electrode pairs in the non-overlapping area of MoS2 is used to determine the light intensity of the polarized light; then the polarization direction of the polarized light is tested by the photocurrent of the first electrode pairs in the non-overlapping area of the two 1T'MoTe2 nanosheets, which specifically includes: first, a certain positive bias is applied to the first electrode pair to suppress the built-in electric field between the 1T'MoTe2 nanosheet and the MoS2 nanosheet under the positive bias and to enhance the built-in electric field between the 1T'MoTe2 nanosheet and the MoS2 nanosheet under the negative bias, and the photocurrent at this time is recorded. According to the photocurrent of the light intensity at this time, two possible polarization directions of the linearly polarized light relative to the molybdenum chain direction of the above-mentioned another nanosheet can be obtained. Then the positive bias on the first electrode pair is changed to a negative bias to suppress the built-in electric field between the 1T'MoTe2 nanosheet and the MoS2 nanosheet under the negative bias and to enhance the built-in electric field between the 1T'MoTe2 nanosheet and the MoS2 nanosheet under the positive bias, and the photocurrent at this time is recorded. According to the photocurrent of the light intensity at this time, two possible polarization directions of the linearly polarized light relative to the above-mentioned another nanosheet can be obtained. When the angle between the molybdenum chain directions of the two layers of 1T'MoTe2 is not 0° or 90°, one pair of the 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 the two 1T'MoTe2 nanosheets is between 5° and 85°. Preferably, the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets is 45°.

[0038] The fitting relationship between the photocurrent and the linear polarization angle under positive bias between the first electrode pair can be expressed as I ph1 =A1cos(2(θ+φ1))+B1, the fitting relationship between photocurrent and 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 = φ2 - φ1 is equal to the angle between the molybdenum chain directions of the two 1T'MoTe2 nanosheets. Since inverse trigonometric functions are required to calculate the polarization angle based on the photocurrent, even small fluctuations in the current near the photocurrent's extreme value can introduce significant errors 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 helps to make angle calculations more accurate.

[0039] Example 2

[0040] A linear polarization direction identification photodetector, such as Figure 2 As shown, Figure 2 The top image is a top view, and the bottom image 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 sequentially;

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

[0042] As a preferred embodiment, the method 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 step in the linear polarization direction identification method as described in Embodiment 1. That is, in Embodiment 1, the identification step after the linearly polarized light is directed onto the nanosheet structure can be automatically implemented by the identification control module.

[0043] As a preferred embodiment, the thickness of both 1T'MoTe2 nanosheets ranges from 3 nm to 100 nm, and the thickness of the MoS2 nanosheets ranges from 3 nm to 100 nm. The thinner thickness of the intermediate MoS2 nanosheet allows for complete ionization during orientation recognition, resulting in higher device response speed and detection rate.

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

[0045] As an implementable manner, the materials of the first electrode pair and the second electrode pair can be Ti, Cr, Au, Ag, Al, etc., and the thicknesses of the first electrode pair and the second electrode pair are between 50-200 nm.

[0046] Embodiment three

[0047] A preparation method of a linear polarization direction recognition photoelectric detector as described above, comprising:

[0048] Providing a substrate;

[0049] Respectively providing 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets, the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets being sequentially located above the substrate, and the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets partially overlapping to form a vertical heterojunction,

[0050] Forming a first electrode pair and a second electrode pair, a first electrode of the first electrode pair being arranged on the substrate and the lower 1T'MoTe2 nanosheet non-laminated area, a second electrode of the first electrode pair being arranged on the substrate and the upper 1T'MoTe2 nanosheet non-laminated area; the second electrode pair being arranged on the substrate and the middle MoS2 nanosheet non-laminated area.

[0051] As an implementable manner, the step of respectively providing 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets, the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets being sequentially located above the substrate, and the 1T'MoTe2 nanosheets, MoS2 nanosheets and 1T'MoTe2 nanosheets partially overlapping to form a vertical heterojunction, comprises the following steps:

[0052] Obtaining MoTe2 nanosheets and MoS2 nanosheets with suitable shapes and thicknesses on the substrate by mechanical exfoliation or chemical vapor deposition;

[0053] The method of using PMMA assisted wet transfer, PVA assisted wet transfer or PDMS dry transfer is used to transfer the nanosheet, first, the 1T'MoTe2 nanosheet is transferred to the target area of the substrate to form a bottom layer, then the MoS2 nanosheet is covered on the MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction, and then the top layer 1T'MoTe2 nanosheet is covered on the 1T'MoTe2 / MoS2 heterojunction to form a 1T'MoTe2 / MoS2 / 1T'MoTe2 vertical heterojunction, wherein the vertical heterojunction bottom layer 1T'MoTe2 nanosheet, MoS2 nanosheet and top layer 1T'MoTe2 nanosheet partially overlap.

[0054] The structure of the application or the structure prepared based on the exemplary method focuses on forming a 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction, and a polarization state identification photodetector with 1T'MoTe2 nanosheet, MoS2 nanosheet and 1T'MoTe2 nanosheet as a heterojunction forms two direction ideal energy Schottky heterojunctions, which can realize fast response of the device, and by virtue of the 1T'MoTe2 semimetal characteristics, wide spectrum detection can be realized.

[0055] The electrode setting mode is realized by film plating processes such as electron beam evaporation, thermal evaporation, magnetron sputtering and atomic layer deposition.

[0056] In addition, after the device is prepared, annealing is carried out under inert gas conditions, specifically, the annealing temperature is 200-400 DEG C, and the annealing time is 1-3h.

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

[0058] Example 1, the steps include:

[0059] Step 1, select a 1cm*1cm size silicon oxide wafer with 300nm oxide layer as a substrate, clean with acetone, ethanol and deionized water in turn and dry for standby.

[0060] Step 2, weigh 5g PVA and dissolve in 95ml deionized water to obtain a PVA solution with a mass fraction of 5%, spin coat the PVA solution on the glass plate at a speed of 500r / min, then dry on a 50 degree hot plate to obtain a PVA film, cut the PVA film to 2mm*2mm size and paste on a 5mm*5mm PDMS film.

[0061] Step 3, select the long strip-shaped single crystal 1T’MoTe2 nanosheet with a thickness of 20 nm prepared by mechanical exfoliation, use the PVA / PDMS film prepared in step 2 to pick up the 1T’MoTe2 nanosheet and transfer it to the target substrate, then heat the substrate to 60 degrees, so that the PVA film carrying the 1T’MoTe2 nanosheet is tightly attached to the substrate, and the PDMS film is removed, and then immersed in deionized water for 1 h to remove PVA.

[0062] Step 4, select the long strip-shaped single crystal MoS2 nanosheet with a thickness of about 10 nm prepared by mechanical exfoliation, use the PVA / PDMS film prepared in step 2 to pick up the MoS2 nanosheet, align the long edge of the MoS2 nanosheet with the long edge of the 1T’MoTe2 nanosheet, and cover the 1T’MoTe2 / MoS2 heterojunction on the 1T’MoTe2 nanosheet, and then immerse in deionized water for 1 h to remove PVA.

[0063] Step 5, select the long strip-shaped single crystal 1T’MoTe2 nanosheet with a thickness of 20 nm prepared by mechanical exfoliation, use the PVA / PDMS film prepared in step 2 to pick up the 1T’MoTe2 nanosheet, and make the angle between the long edge of the 1T’MoTe2 nanosheet and the long edge of the 1T’MoTe2 on the substrate be 60 degrees and cover the 1T’MoTe2 / MoS2 / 1T’MoTe2 heterojunction on the 1T’MoTe2 / MoS2 heterojunction, and then immerse in deionized water for 1 h to remove PVA.

[0064] Step 6, prepare the first electrode pair and the second electrode pair. Spin-coat electron beam resist on the substrate with the heterojunction for electron beam lithography, and then develop the patterned electrodes after developing treatment. Use electron beam evaporation to deposit 10 nm Cr and 50 nm Au, and then remove the glue to obtain the deposited electrodes.

[0065] Step 7, anneal the device. Place the device in a tube furnace for annealing, use argon for protection during annealing, argon flow rate is 1 slm, annealing temperature is 250 degrees, and annealing time is 2 h.

[0066] Example two, the steps include:

[0067] Step 1, select a 1 cm x 1 cm size quartz substrate, clean it with acetone, ethanol, and deionized water in turn, and then dry it for standby use.

[0068] Step 2, select a 5 mm x 5 mm size PDMS film as a stamp for transferring nanosheets.

[0069] Step 3, select the thickness of 20 nm of single crystal 1T'MoTe2 nanosheet grown by CVD, find the x axis direction of the nanosheet, etch the nanosheet into a long strip, use the PDMS film to pick up the 1T'MoTe2 nanosheet, and transfer it to the target substrate, then heat the substrate to 80 degrees, keep it for 20 min, then the PDMS loses adhesion, and remove the PDMS film, so that the 1T'MoTe2 nanosheet remains on the substrate.

[0070] Step 4, select the thickness of 10 nm of single crystal MoS2 nanosheet grown by CVD, etch the nanosheet into a long strip, use the PDMS film to pick up the MoS2 nanosheet, align the long side of the MoS2 nanosheet with the long side of the 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 min, then the PDMS loses adhesion, and remove the PDMS film.

[0071] Step 5, select the thickness of 20 nm of single crystal 1T'MoTe2 nanosheet grown by CVD, find the x axis direction of the nanosheet, etch the nanosheet into a long strip, use the PDMS film to pick up the 1T'MoTe2 nanosheet, make the long side of the 1T'MoTe2 nanosheet at an angle of 45 degrees with the long side of the 1T'MoTe2 on the substrate and cover it on 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 min, then the PDMS loses adhesion, and remove the PDMS film.

[0072] Step 6, prepare the first electrode pair and the second electrode pair. Perform maskless laser direct writing lithography on the photoresist on the substrate with the heterojunction, and then develop the patterned electrodes after development. Use thermal evaporation to deposit 10 nm Ti and 100 nm Au, then remove the glue to get the deposited electrodes.

[0073] Step 7, anneal the device. Place the device in a tube furnace for annealing, use 5% hydrogen concentration of argon-hydrogen mixture for protection during annealing, flow rate is 1 slm, annealing temperature is 300 degrees, annealing time is 1.5 h.

[0074] Overall, the present application solves the problem of polarization direction recognition in the current linear polarization detection. The current polarization light detector is mainly divided into time-sharing type polarization photoelectric detector and focal plane type polarization photoelectric detector. They have problems such as complex preparation process, need to use polaroid or half-wave plate to cause large equipment volume, and cannot realize real-time detection. The present application uses vertically stacked 1T'MoTe2 / MoS2 / 1T'MoTe2 heterojunction, and by means of the polarization sensitivity of 1T'MoTe2 itself, the polarization direction of incident polarized light can be inferred by applying two opposite direction bias. The polarization angle recognition on-chip integration can be realized without using polaroid or half-wave plate. The detection volume is reduced, and on-chip integration is realized.

[0075] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A linear polarization direction identification method, characterized in that, The method comprises the following steps: A linearly polarized light to be measured is shot to a nanosheet structure composed of a first 1T' MoTe2 nanosheet, a MoS2 nanosheet and a second 1T' MoTe2 nanosheet which are stacked in sequence, wherein the three layers of nanosheets are partially overlapped; one electrode is arranged on each of the two 1T' MoTe2 nanosheets to form a first electrode pair; two electrodes are arranged on the MoS2 nanosheet to form a second electrode pair; the included angle between the molybdenum chain directions of the two 1T' MoTe2 nanosheets is not 0° or 90°; After a preset voltage is applied 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 pre-calibrated photocurrent-light intensity relationship under the preset voltage; A forward bias is applied to the first electrode pair, and a second photocurrent between the first electrode pair is collected, and two candidate polarization directions of the linearly polarized light to be measured are determined according to the pre-calibrated relationship between the second photocurrent and the polarization direction under the light intensity; a negative bias is applied to the first electrode pair, and a third photocurrent between the first electrode pair is collected, and another two candidate polarization directions of the linearly polarized light to be measured are determined according to the pre-calibrated relationship between the third photocurrent and the polarization direction under the light intensity; two same polarization directions in the four candidate polarization directions are the polarization direction of the linearly polarized light to be measured, and the identification is completed.

2. The linear polarization direction identification method according to claim 1, characterized in that, The included angle between the molybdenum chain directions of the two 1T' MoTe2 nanosheets is between 5° and 85°.

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

4. A linear polarization direction discrimination photodetector, characterized in that, The method comprises the following steps: A nanosheet structure composed of a first 1T' MoTe2 nanosheet, a MoS2 nanosheet and a second 1T' MoTe2 nanosheet which are stacked in sequence; Wherein the three layers of nanosheets are partially overlapped; one electrode is arranged on each of the two 1T' MoTe2 nanosheets to form a first electrode pair; two electrodes are arranged on the MoS2 nanosheet to form a second electrode pair; the included angle between the molybdenum chain directions of the two 1T' MoTe2 nanosheets is not 0° or 90°.

5. The linearly polarized direction identification photodetector according to claim 4, characterized in that, Further comprising an identification control module; The identification control module is connected to the first electrode pair and the second electrode pair, and is used for performing the direction identification operation steps in the linear polarization direction identification method of claim 1.

6. The linearly polarized direction identification photodetector according to claim 4, characterized in that, 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.

7. The linearly polarized direction identification photodetector according to claim 4, characterized in that, The included angle between the molybdenum chain directions of the two 1T' MoTe2 nanosheets is between 5° and 85°. 8.The linearly polarized direction identification photodetector according to claim 4, wherein, The included angle between the molybdenum chain directions of the two 1T' MoTe2 nanosheets is 45°.

9. A method of fabricating a linearly polarized direction-identified photodetector as claimed in any one of claims 4 to 8, characterized in that, The method comprises the following steps: 1T' MoTe2 nanosheets and MoS2 nanosheets with required shapes and thicknesses are obtained on a substrate by a mechanical exfoliation method or a chemical vapor deposition method; The method of PMMA-assisted wet transfer, PVA-assisted wet transfer or PDMS dry transfer is used for transferring the nanosheet, first, one of the 1T'MoTe2 nanosheet is transferred to the target area of the substrate, then the MoS2 nanosheet is covered on the 1T'MoTe2 nanosheet to form a 1T'MoTe2 / MoS2 heterojunction, and 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, the MoS2 nanosheet and the top 1T'MoTe2 nanosheet in the vertical heterojunction partially overlap.

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