Linear polarization sensitive photoelectric detector based on electromechanical coupling field regulation and its preparation method

Abstract

The present invention belongs to the technical field of optoelectronic devices, and in particular, relates to a linear polarization sensitive photodetector based on electromechanical coupling field regulation and a preparation method thereof, wherein the photodetector comprises, from bottom to top, a flexible substrate layer, a palladium diselenide layer, a ReX2 layer (X=S, Se) and a flexible ferroelectric material layer; the palladium diselenide layer and the ReX2 layer (X=S, Se) together constitute a heterojunction structure; a source metal electrode is arranged on the palladium diselenide layer, a drain metal electrode is arranged on the ReX2 layer (X=S, Se), and a gate metal electrode is arranged on the flexible ferroelectric material layer. The present invention regulates the polarization characteristics of the heterojunction photodetector through ferroelectric polarization / strain field, improves the dichroic ratio of the photogenerated current, makes it greater than 20, and breaks through the bottleneck of existing devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and in particular relates to a linear polarization-sensitive photoelectric detector based on electromechanical coupling field regulation and a preparation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] As an important information carrier, light waves contain information such as intensity, frequency, phase and polarization. Usually, the intensity and wavelength information of light are mainly encoded into brightness and spectrum for imaging. In addition, targets on the surface or in the atmosphere in nature will generate specific polarization information determined by their own characteristics when reflecting, scattering, transmitting and radiating electromagnetic waves, and these polarization information can be used to analyze the shape, surface roughness, texture direction and physical and chemical properties of the target. As an important supplement to intensity detection, polarization detection can expand the amount of information from three dimensions (light intensity, spectrum and space) to seven dimensions (light intensity, spectrum, space, polarization degree, polarization azimuth, polarization ellipticity and rotation direction). It can effectively suppress background noise. The difference in polarization characteristics between the target and the background will lead to obvious differences in polarization contrast, which can increase the recognition effect and distance of the object. Therefore, polarization imaging technology has important application value in industrial detection, biomedicine, earth remote sensing, modern military, aviation and ocean.

[0004] An effective way to realize miniature and highly integrated polarization light detectors is to use semiconductor materials that are inherently sensitive to polarization light as the working medium of the active layer of the detector. The anisotropy of the crystal structure of some two-dimensional semiconductor materials that have emerged in recent years makes them significantly sensitive to polarization light, which has important potential application value in the field of polarization detectors and provides a new platform for the realization of polarization detection. The photocurrent dichroic ratio (PDR, the ratio of the maximum and minimum photocurrent under linearly polarized incident light in different directions) is the core indicator for measuring the polarization sensitivity of the device, which directly reflects the quality of its polarization detection imaging ability. The PDR of typical polarization detectors based on different anisotropic two-dimensional materials reported so far is mostly below 5.0 (especially in the infrared band), and some are greater than 10, concentrated in the visible light band. Such performance has become an important bottleneck restricting the practical application of related detectors (PDR>20). Therefore, the current two-dimensional material linear polarization detectors have bottleneck problems such as low photocurrent dichroic ratio and difficulty in meeting social needs. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a linear polarization-sensitive photoelectric detector based on electromechanical coupling field regulation and a preparation method thereof.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present invention provides a linear polarization sensitive photodetector based on electromechanical coupling field regulation, the photodetector comprises, from bottom to top, a flexible substrate layer, a palladium diselenide layer, a ReX2 layer (X = S, Se) and a flexible ferroelectric material layer;

[0008] The palladium diselenide layer and the ReX2 layer (X=S, Se) together form a heterojunction structure;

[0009] A source metal electrode is arranged on the palladium diselenide layer, a drain metal electrode is arranged on the ReX2 layer (X=S, Se), and a gate metal electrode is arranged on the flexible ferroelectric material layer.

[0010] The second aspect of the present invention provides a method for preparing a linear polarization-sensitive photodetector based on electromechanical coupling field regulation, comprising:

[0011] (1) Prepare the PdSe2 film by mechanical exfoliation or CVD, and cover the PdSe2 film on the flexible substrate by directional transfer technology;

[0012] (2) ReX2 is prepared by mechanical stripping technology or CVD technology, and ReX2 is transferred to the PdSe2 film by dry or wet transfer technology, and then cleaned with organic solvents such as acetone and deionized water, and dried with nitrogen gas;

[0013] (3) Using standard photolithography process, spin-coating photoresist, positioning the ReX2 / PdSe2 heterojunction under the photolithography machine, using a photolithography mask for exposure, and then developing;

[0014] (4) using an electron beam evaporation device to evaporate a source electrode metal material and a drain electrode metal material on the palladium diselenide layer and the ReX2 layer (X = S, Se), respectively, and then stripping the photoresist with an organic solvent, cleaning, and forming a source and drain electrode;

[0015] (5) using spin coating or Langmuir-Blodgett (LB) technology to prepare a ferroelectric material layer as a gate dielectric on the ReX2 / PdSe2 heterojunction structure;

[0016] (6) A transparent electrode is evaporated on the ferroelectric material as a gate.

[0017] One or more of the above technical solutions have the following beneficial effects:

[0018] (1) The present invention regulates the polarization characteristics of heterojunction photodetectors through ferroelectric polarization / strain fields, improves the photocurrent dichroism ratio to be greater than 20, and breaks through the bottleneck of existing devices. The device has a simple structure, low cost, small size, and is easy to integrate.

[0019] (2) The detector of the present invention uses ferroelectric materials for gate control. The ferroelectric polarization electric field strength is much greater than the traditional gate field. At the same time, the residual polarization field of the material can be used to regulate the device. The electric field has the advantage of being non-volatile, which significantly reduces energy consumption.

[0020] (3) The detector of the present invention adopts a flexible substrate through a strain control device, which can also meet the requirements of ultra-thin and flexible detection.

[0021] (4) The detector structure of the present invention conforms to the development trend of detector miniaturization, easy integration, energy saving and flexibility, and can expand the frontier research field of new semiconductor optoelectronic devices.

[0022] (5) The photodetector of the present invention is small in size and can detect light from visible light to infrared light (0.4 microns to 1.6 microns). The detection spectrum range can be regulated by the electromechanical coupling field. The photoelectric response characteristics can be regulated by the gate voltage.

[0023] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 This is a schematic diagram of the structure of a linear polarization-sensitive photodetector based on electromechanical coupling field regulation according to the first embodiment.

[0026] Figure 2 The graphs are the variation curves of the normalized photocurrent of the detector of the first embodiment with the polarization angle of the incident light under different electromechanical coupling fields. DETAILED DESCRIPTION

[0027] Embodiment 1

[0028] like Figure 1 As shown, this embodiment discloses a linear polarization sensitive photodetector based on electromechanical coupling field regulation, and the photodetector includes, from bottom to top, a flexible substrate layer, a palladium diselenide layer (PdSe2), a ReX2 layer (X=S, Se), and a flexible ferroelectric material layer; the palladium diselenide layer and the ReX2 layer (X=S, Se) together form a heterojunction structure;

[0029] A source metal electrode is arranged on the palladium diselenide layer, a drain metal electrode is arranged on the ReX2 layer, and a gate metal electrode is arranged on the flexible ferroelectric material layer.

[0030] Furthermore, the flexible substrate may be polydimethylsiloxane (PDMS) or polyimide. The present invention uses a flexible substrate through a strain control device to meet the requirements of ultra-thin and flexible detection.

[0031] Furthermore, the flexible ferroelectric material is P(VDF-TrFE).

[0032] Furthermore, ReX2 is a single layer or multiple layers, and PdSe2 is a single layer or multiple layers. The thickness of the ReX2 layer and the PdSe2 layer are increased by multi-layer stacking. The maximum thickness of the ReX2 layer is 40nm, and the maximum thickness of the PdSe2 layer is 50nm. ReX2 and PdSe2 are layered materials, and the specific thickness is about 0.65nm.

[0033] Furthermore, the source and drain are made of one or more of gold, silver, indium, copper, titanium, etc., and serve as lead-out electrodes connected to an external circuit; the transparent gate may be made of metals such as aluminum; the present invention utilizes ferroelectric materials for gate control, and the ferroelectric polarization electric field strength is much greater than that of traditional gate fields. At the same time, the residual polarization field of the material can be used to regulate the device, and the electric field has the advantage of non-volatility, which significantly reduces energy consumption.

[0034] The present invention can achieve a change in the polarization photocurrent ratio within the range of 1-20 by regulating the ferroelectric polarization field and the strain field electromechanical coupling field. The strain is introduced through the flexible substrate, and the strain can be introduced by stretching or bending the flexible substrate. The electromechanical coupling field is used to regulate the device band structure and polarization absorption anisotropy to improve the photocurrent ratio.

[0035] The present invention utilizes the strain field and the ferroelectric polarization field to achieve a wide range of control of the dichroic ratio of the detector's photogenerated current. Figure 2 As shown, the normalized photocurrent of the device changes with the incident polarization angle.

[0036] Specifically, in this embodiment, the thickness of PdSe2 is 10nm, the thickness of ReX2 is 5.0nm, the flexible substrate is polyimide with a thickness of 10μm, the ferroelectric material is P(VDF-TrFE) with a thickness of 200nm, the source and drain metals are Cr / Au (5 / 50nm), and the gate metal is aluminum (50nm). Under the condition of no strain and no polarization field, the photogenerated current dichroism ratio of the detector is 2.8; after 2% tensile strain and superposition of the upward polarization electric field, the photogenerated current dichroism ratio is 7.0; after 2% compressive strain and superposition of the downward polarization electric field, the photogenerated current dichroism ratio reaches about 20. Therefore, the photogenerated current dichroism ratio of the device can be changed by regulating the electromechanical coupling field.

[0037] Embodiment 2

[0038] This embodiment discloses a method for preparing a linear polarization-sensitive photoelectric detector based on electromechanical coupling field regulation, comprising the following steps:

[0039] (1) Prepare a PDMS or polyimide flexible substrate with a thickness of tens of microns;

[0040] (2) preparing the PdSe2 film by mechanical exfoliation or CVD, and covering the PdSe2 film on the flexible substrate by directional transfer technology;

[0041] (3) ReX2 of a certain thickness is prepared by mechanical stripping technology or CVD technology, and ReX2 is transferred to the PdSe2 film by dry or wet transfer technology, and then cleaned with organic solvents such as acetone and deionized water, and dried with nitrogen gas;

[0042] (4) Using standard photolithography process, spin-coating photoresist, positioning the ReX2 / PdSe2 heterojunction under the photolithography machine, using a photolithography mask for exposure, and then developing;

[0043] (5) Using electron beam evaporation equipment to evaporate the metal materials of the source and drain electrodes, first evaporate 10 nm thick titanium metal, and then evaporate 50 nm thick gold on the titanium metal, so as to enhance the stability and conductivity of the titanium metal, and then use an organic solvent to strip the photoresist, clean it, and form the source and drain electrodes;

[0044] (6) Using spin coating or Langmuir-Blodgett (LB) technology to prepare organic ferroelectric polymer P (VDF-TrFE) as gate dielectric at ReX2 / PdSe2 heterojunction.

[0045] (7) Finally, a transparent electrode is evaporated on the ferroelectric material as a gate.

[0046] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A linear polarization-sensitive photodetector based on electromechanical coupling field regulation, characterized in that: The photodetector comprises, from bottom to top, a flexible substrate layer, a palladium diselenide layer, a ReX2 layer and a flexible ferroelectric material layer; wherein X=S, Se; The palladium diselenide layer and the ReX2 layer together form a heterojunction structure; The thickness of the palladium diselenide layer is 10 nm, and the thickness of the ReX2 layer is 5 nm; A source metal electrode is arranged on the palladium diselenide layer, a drain metal electrode is arranged on the ReX2 layer, and a gate metal electrode is arranged on the flexible ferroelectric material layer; the source metal electrode and the drain metal electrode are made of Cr / Au, the thickness of Cr is 5nm, the thickness of Au is 50nm, and they serve as extraction electrodes connected to an external circuit; the gate metal electrode is aluminum, with a thickness of 50nm; The flexible substrate layer is polyimide with a thickness of 10 μm, and the flexible substrate regulates the photodetector by strain; The strain is introduced through the flexible substrate, and the strain can be introduced by stretching or bending the flexible substrate; The flexible ferroelectric material layer is P (VDF-TrFE) with a thickness of 200 nm; The photodetector has a dichroic ratio of 2.8 under no strain and no polarization field; 7.0 under 2% tensile strain and an upward polarization electric field; and 20 under 2% compressive strain and a downward polarization electric field. The polarization characteristics of the heterojunction photodetector are regulated by the ferroelectric polarization field and the strain field electromechanical coupling field to improve the dichroic ratio of the photogenerated current.

2. The method for preparing a linear polarization-sensitive photodetector based on electromechanical coupling field regulation according to claim 1, characterized in that: include: (1) Prepare PdSe2 thin film by mechanical exfoliation or CVD method, and cover the PdSe2 thin film on the flexible substrate by directional transfer technology; (2) ReX2 is prepared by mechanical stripping technology or CVD technology, and ReX2 is transferred to the PdSe2 film by dry or wet transfer technology, and then cleaned with acetone and deionized water and dried with nitrogen; (3) Using standard photolithography process, spin-coating photoresist, positioning the ReX2 / PdSe2 heterojunction under the photolithography machine, using a photolithography mask for exposure, and then developing; (4) using an electron beam evaporation device to evaporate a source metal electrode and a drain metal electrode on the palladium diselenide layer and the ReX2 layer respectively, and then stripping the photoresist with an organic solvent, cleaning, and forming a source and a drain electrode; (5) Using spin coating or Langmuir-Blodgett technology to prepare a ferroelectric material layer as a gate dielectric on the ReX2 / PdSe2 heterojunction structure; (6) Evaporate a transparent electrode on the ferroelectric material as a gate.

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