A ferroelectric local field enhanced polarization photodetector and a preparation method thereof

Abstract

The application discloses a ferroelectric local field enhanced polarized photoelectric detector and a preparation method thereof, and relates to the technical field of polarized photoelectric detection. The polarized photoelectric detector is observed from bottom to top and sequentially comprises a substrate, a two-dimensional semiconductor layer, a metal electrode pair and a ferroelectric film layer. The material of the two-dimensional semiconductor layer is black phosphorus. The material of the ferroelectric film layer is polyvinyl fluoride-based ferroelectric polymer. The metal electrode pair comprises a first metal electrode and a second metal electrode. A channel structure formed between the first metal electrode and the second metal electrode exposes part of the two-dimensional semiconductor layer. An in-plane PN junction is formed by part of the two-dimensional semiconductor layer exposed after the ferroelectric film layer is electrode polarized. The strong local field of the ferroelectric film changes the Seebeck coefficient and the conductivity of the black phosphorus in the armchair direction and the zigzag direction, enhances the photocurrent in the armchair direction, and greatly improves the polarization detection ratio of the polarized photoelectric detector.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polarized photoelectric detection, in particular to a ferroelectric local field enhanced polarized photoelectric detector and a preparation method thereof. BACKGROUND

[0002] Generally, photoelectric detectors can detect information in three aspects of light intensity, spectrum and space, but for polarized photoelectric detectors, the dimension of the collected information can be increased by detecting the degree of polarization, the azimuth angle of polarization, the ellipticity of polarization and the direction of rotation. The ratio of the maximum photocurrent to the minimum photocurrent obtained when the polarization angle of light is changed is defined as the polarization detection ratio (PR) of the polarized photoelectric detector, which represents the polarization sensitivity of the polarized photoelectric detector. The larger the polarization detection ratio is, the more sensitive the polarized photoelectric detector is to polarized light.

[0003] Polarization detection technology is widely used and has important applications in aerospace remote sensing, target detection, biomedicine, bionic vision and the like. At present, for polarization detection, complex optical systems are added to the detection system, and time-sharing technology, aperture-sharing technology and amplitude-sharing technology are used to extract polarization information, but such a polarization detection system inevitably has problems of slow response speed, low spatial resolution and low response rate. Although metal nanograting and filtering structure can be designed on the traditional detector to enhance the polarization absorption of light, such a process is complicated and is not conducive to integration in a micro-nano photoelectric system.

[0004] With the emergence of two-dimensional semiconductor materials with anisotropic crystal structure, such as ReS2, ReSe2, GeSe and black phosphorous (BP), low-dimensional material polarized photoelectric detectors with relatively simple process preparation, polarization photoelectric detection and easy integration into micro-nano systems have also emerged. Among them, black phosphorous is a two-dimensional layered structure material composed of a single phosphorus element. The boundary of black phosphorus atoms in the layer is arranged in a "hand chair" and zigzag shape in the armchair and zigzag directions, respectively. Black phosphorous is a narrow-bandgap direct-bandgap semiconductor with high light absorption efficiency and high light emission efficiency, and has a wide detection range, including the visible light band to the near-infrared band. However, the polarization detection ratio of the existing black phosphorous polarization detector is not high (generally less than 10), which greatly limits the practical application of the black phosphorous polarization detector. SUMMARY

[0005] The purpose of the present application is to provide a ferroelectric local field enhanced polarized photoelectric detector and a preparation method thereof, so as to improve the polarization detection ratio.

[0006] To achieve the above purpose, the present application provides the following solutions:

[0007] A ferroelectric local field enhanced polarization photodetector, observed from bottom to top, is a substrate, a two-dimensional semiconductor layer, a metal electrode pair and a ferroelectric thin film layer in sequence;

[0008] The material of the two-dimensional semiconductor layer is black phosphorus; and the material of the ferroelectric thin film layer is polyvinylidene fluoride-based ferroelectric polymer.

[0009] The metal electrode pair includes a first metal electrode and a second metal electrode; a channel structure formed between the first metal electrode and the second metal electrode exposes part of the two-dimensional semiconductor layer; and an in-plane PN junction is formed by part of the two-dimensional semiconductor layer exposed after the ferroelectric thin film layer is polarized.

[0010] Optionally, the substrate includes a silicon substrate and a silicon dioxide layer arranged on the silicon substrate; and the thickness of the substrate is 0.3-0.5 mm.

[0011] Optionally, the thickness of the two-dimensional semiconductor layer is 5-15 nm, and the thickness of the ferroelectric thin film layer is 50-200 nm.

[0012] Optionally, the first metal electrode and the second metal electrode are both chromium-gold composite electrodes; the chromium-gold composite electrode includes a chromium layer and a gold layer arranged on the chromium layer; the thickness of the chromium layer is 10 nm, and the thickness of the gold layer is 20 nm.

[0013] A preparation method of a ferroelectric local field enhanced polarization photodetector, comprising:

[0014] A two-dimensional semiconductor material is transferred to a substrate surface by a mechanical exfoliation transfer process to generate a two-dimensional semiconductor layer; the two-dimensional semiconductor material is black phosphorus.

[0015] A metal electrode pair is prepared on the two-dimensional semiconductor layer by an electron beam lithography technology, a thermal evaporation metal process and an exfoliation process; the metal electrode pair includes a first metal electrode and a second metal electrode; and a channel structure is formed between the first metal electrode and the second metal electrode.

[0016] A ferroelectric thin film layer is prepared on a target device by a spin coating process to obtain a target sample; the material of the ferroelectric thin film layer is polyvinylidene fluoride-based ferroelectric polymer; and the target device includes the substrate, the two-dimensional semiconductor layer arranged on the substrate and the metal electrode pair arranged on the two-dimensional semiconductor layer.

[0017] Optionally, the method further comprises:

[0018] The ferroelectric thin film layer in the target sample is polarized by a piezoelectric force microscope, so that the two-dimensional semiconductor layer exposed by the channel structure forms an in-plane PN junction.

[0019] Optionally, the mechanical exfoliation transfer process is used to transfer the two-dimensional semiconductor material to the surface of the substrate to generate the two-dimensional semiconductor layer, specifically including:

[0020] The mechanical exfoliation transfer process is used to transfer the two-dimensional semiconductor material to the surface of the substrate to generate the two-dimensional semiconductor layer in a glove box with a nitrogen atmosphere;

[0021] The substrate includes a silicon substrate and a silicon dioxide layer arranged on the silicon substrate; and the thickness of the two-dimensional semiconductor layer is 5-15 nanometers.

[0022] Optionally, the electron beam lithography technology, the thermal evaporation metal process and the exfoliation process are used to prepare a pair of metal electrodes on the two-dimensional semiconductor layer, specifically including:

[0023] The electron beam lithography technology is used to prepare a metal electrode pattern on the two-dimensional semiconductor layer;

[0024] The thermal evaporation metal process is used to prepare a sample metal electrode on the metal electrode pattern;

[0025] The exfoliation process is used to exfoliate the metal film on the sample metal electrode to obtain a pair of metal electrodes;

[0026] The first metal electrode and the second metal electrode are both chromium-gold composite electrodes; the chromium-gold composite electrode includes a chromium layer and a gold layer arranged on the chromium layer; the thickness of the chromium layer is 10 nanometers, and the thickness of the gold layer is 20 nanometers.

[0027] Optionally, the spin coating process is used to prepare a ferroelectric thin film layer on the target device to obtain a target sample, specifically including:

[0028] The spin coating process is used to prepare a ferroelectric thin film layer on the target device in a glove box with a nitrogen atmosphere to obtain a preliminary target sample;

[0029] The preliminary target sample is placed on a hot plate and annealed at 135°C for 2-4 hours to obtain a final target sample; the thickness of the ferroelectric thin film layer is 50-200 nanometers.

[0030] Optionally, the ferroelectric thin film layer in the target sample is polarized by using a piezo force microscope, so that the two-dimensional semiconductor layer exposed by the channel structure forms an in-plane PN junction to obtain a polarized photodetector, specifically including:

[0031] The conductive probe in the piezo force microscope is used to scan the target sample in a contact mode to determine the ferroelectric thin film layer;

[0032] The voltage generated by the signal generator is applied to the ferroelectric film layer through the conductive probe, so as to regulate the target two-dimensional semiconductor layer to be electron conductive and hole conductive respectively, and finally make the target two-dimensional semiconductor layer form an in-plane PN junction, and obtain the polarized photoelectric detector.

[0033] Wherein, a positive voltage is applied to one side of the ferroelectric film layer, and a negative voltage is applied to the other side of the ferroelectric film layer.

[0034] According to the specific embodiments of the present application, the following technical effects are disclosed.

[0035] The strong electric field of the ferroelectric local field is used to regulate the anisotropic two-dimensional semiconductor material, i.e. black phosphorus, that is, the strong local field of the ferroelectric film is used to change the Seebeck coefficient and conductivity of black phosphorus in the armchair direction and zigzag direction, so as to enhance the photocurrent in the armchair direction, greatly improve the polarization detection ratio of the polarized photoelectric detector, and realize the polarized photoelectric detector with high polarization detection ratio. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0037] Figure 1 The cross-sectional schematic diagram of the polarized photoelectric detector with ferroelectric local field enhancement according to the embodiments of the present application;

[0038] Figure 2 The flowchart of the preparation method of the polarized photoelectric detector with ferroelectric local field enhancement according to the embodiments of the present application;

[0039] Figure 3 The working condition diagram of the polarized photoelectric detector with ferroelectric local field enhancement according to the embodiments of the present application under polarized light illumination;

[0040] Figure 4 The current-voltage characteristic curve diagram of the polarized photoelectric detector with ferroelectric local field enhancement according to the embodiments of the present application under dark state and light illumination;

[0041] Figure 5 The photoelectric current characteristic curve diagram of the polarized photoelectric detector with ferroelectric local field enhancement according to the embodiments of the present application with the change of the polarization light angle.

[0042] In the figure: substrate 1, two-dimensional semiconductor layer 2, first metal electrode 31, second metal electrode 32, ferroelectric film layer 4, half-wave plate 5, polarizer 6. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Ferroelectric thin films (polyvinylidene fluoride ferroelectric polymer, P(VDF-TrFE)) are stable and easily prepared polymer thin film materials with excellent properties and adaptability to various geometries. A 300 nm ferroelectric thin film exhibits a remanent polarization of approximately 7 μC / cm at room temperature. 2 The coercive voltage is approximately 22.5V, and the coercive electric field is 7.5 × 10⁻⁶. 7 V / m. Ferroelectric thin films can be prepared by spin-coating. They have a low crystallization temperature (about 130℃~140℃), can be combined with most substrates, and have properties suitable for manipulating two-dimensional semiconductor materials. Based on the above characteristics, high-performance optoelectronic devices can be prepared.

[0045] Based on this, the present invention provides a ferroelectric localized field-enhanced polarization photodetector and its fabrication method. This polarization photodetector utilizes the strong localized field of the ferroelectric thin film to alter the Seebeck coefficient and conductivity of black phosphorus in the armchair and zigzag directions, thereby enhancing the photocurrent in the armchair direction and significantly improving the polarization detectivity of the photodetector. Such a polarization photodetector achieves a maximum polarization detectivity exceeding two orders of magnitude at room temperature, exhibits stable performance, and has a detection range from the visible light band to the near-infrared band.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] This invention relates to an anisotropic two-dimensional material in-plane PN junction, specifically a ferroelectric localized field enhanced polarization photodetector. The polarization photodetector provided by this invention is easy to integrate into micro-nano systems and has significant implications for applications in industry, people's livelihood, and national defense.

[0049] This invention utilizes a strong local field to alter the lattice vibrations of black phosphorus, thereby enhancing its anisotropy and producing a low-dimensional material polarization photodetector with high polarization detectivity, stable performance, and a wide response range.

[0050] likeFigure 1 As shown, this embodiment provides a polarization photodetector with enhanced ferroelectric local field. From bottom to top, the layers are substrate 1, two-dimensional semiconductor layer 2, metal electrode pair, and ferroelectric thin film layer 4.

[0051] The material of the two-dimensional semiconductor layer 2 is an anisotropic two-dimensional semiconductor material, preferably black phosphorus; the material of the ferroelectric thin film layer 4 is polyvinylidene fluoride ferroelectric polymer; the metal electrode pair includes a first metal electrode 31 and a second metal electrode 32; the channel structure formed between the first metal electrode 31 and the second metal electrode 32 exposes a portion of the two-dimensional semiconductor layer; wherein, the portion of the two-dimensional semiconductor layer exposed after polarization of the ferroelectric thin film layer 4 forms an in-plane PN junction.

[0052] In one example, the substrate 1 includes a silicon substrate and a silicon dioxide layer disposed on the silicon substrate; the thickness of the substrate 1 is 0.3-0.5 mm, and the thickness of the silicon dioxide layer is 285 nanometers.

[0053] In one example, the thickness of the two-dimensional semiconductor layer 2 is 5-15 nanometers.

[0054] In one example, both the first metal electrode 31 and the second metal electrode 32 are chromium-gold composite electrodes; the chromium-gold composite electrode includes a chromium layer and a gold layer disposed on the chromium layer; wherein the thickness of the chromium layer is 10 nanometers and the thickness of the gold layer is 20 nanometers. The first metal electrode 31 and the second metal electrode 32 are the source and drain electrodes respectively in contact with the two-dimensional semiconductor layer 2.

[0055] In one example, the thickness of the ferroelectric thin film layer 4 is 50-200 nanometers.

[0056] Example 2

[0057] like Figure 2 As shown, this embodiment of the invention provides a method for fabricating a polarization photodetector with enhanced ferroelectric local field as described in Embodiment 1, comprising:

[0058] Step 201: A two-dimensional semiconductor material is transferred to the substrate surface using a mechanical peeling and transfer process to generate a two-dimensional semiconductor layer; the two-dimensional semiconductor material is black phosphorus.

[0059] Step 202: A metal electrode pair is fabricated on the two-dimensional semiconductor layer using electron beam lithography, thermal evaporation metal processing, and a lift-off process; the metal electrode pair includes a first metal electrode and a second metal electrode; and a channel structure is formed between the first metal electrode and the second metal electrode.

[0060] Step 203: a ferroelectric thin film layer is prepared on the target device by a spin coating process to obtain a target sample; the material of the ferroelectric thin film layer is polyvinylidene fluoride-based ferroelectric polymer; the target device comprises the substrate, a two-dimensional semiconductor layer arranged on the substrate, and a metal electrode pair arranged on the two-dimensional semiconductor layer.

[0061] Further, the preparation method provided in the embodiment further comprises: polarizing the ferroelectric thin film layer in the target sample by a piezo-force microscope, so that the two-dimensional semiconductor layer exposed by the channel structure forms an in-plane PN junction.

[0062] Specifically, step 201 comprises:

[0063] The two-dimensional semiconductor material is transferred to the surface of the substrate in a glove box with a nitrogen atmosphere by a mechanical exfoliation transfer process to generate a two-dimensional semiconductor layer. The substrate comprises a silicon substrate and a silicon dioxide layer arranged on the silicon substrate; the thickness of the substrate is 0.3-0.5 mm, and the thickness of the silicon dioxide layer is 285 nm.

[0064] Specifically, step 202 comprises:

[0065] A metal electrode pattern is prepared on the two-dimensional semiconductor layer by an electron beam lithography technique.

[0066] A sample metal electrode is prepared on the metal electrode pattern by a thermal evaporation metal process.

[0067] A metal electrode pair is obtained by peeling off the metal film on the sample metal electrode by a peeling process.

[0068] Specifically, the first metal electrode and the second metal electrode are both chromium-gold composite electrodes; the chromium-gold composite electrode comprises a chromium layer and a gold layer arranged on the chromium layer; the thickness of the chromium layer is 10 nm, and the thickness of the gold layer is 20 nm.

[0069] Specifically, step 203 comprises:

[0070] In a glove box with a nitrogen atmosphere, a ferroelectric thin film layer is prepared on a target device by a spin coating process to obtain a preliminary target sample; then the preliminary target sample is placed on a hot plate and annealed at 135°C for 2-4 hours to obtain a final target sample; the thickness of the ferroelectric thin film layer is 50-200 nm.

[0071] Specifically, the step of polarizing the ferroelectric thin film layer in the target sample by a piezo-force microscope so that the two-dimensional semiconductor layer exposed by the channel structure forms an in-plane PN junction comprises:

[0072] The conductive probe in the piezoelectric force microscope is scanned on the target sample in a contact mode to determine the ferroelectric film layer; and the voltage generated by a signal generator is applied to the ferroelectric film layer through the conductive probe, so that the target two-dimensional semiconductor layer is respectively controlled to be electron conductive and hole conductive, and finally the target two-dimensional semiconductor layer forms an in-plane PN junction to obtain a polarized photodetector; wherein a positive voltage is applied to one side of the ferroelectric film layer, and a negative voltage is applied to the other side of the ferroelectric film layer.

[0073] One example is: the target sample is placed in the piezoelectric force microscope operation table, first the probe scans out the channel part of the target sample, and then the scanning range, voltage polarity and size are set according to the topography of the target sample. During polarization, the corresponding P(VDF-TrFE) on the left side of the black phosphorus channel is applied with a scanning voltage of (+15)-(+25) V, and the right side is applied with a scanning voltage of (-15)-(-25) V, and the scanning frequency is 2 Hz.

[0074] The advantage of the embodiment of the present application is that the ferroelectric film is a thin film material which is convenient and fast to prepare, and is very easy to combine with various two-dimensional semiconductor materials. Here, the residual polarization field of the ferroelectric film material is used to form electron injection and hole injection on the left and right parts of the black phosphorus channel at the same time, and the residual polarization field is very stable, without the need for an external gate voltage, thereby reducing the power consumption of the device. Due to the strong residual polarization electric field and good fatigue characteristics of the ferroelectric film, the control method has a remarkable effect and can be repeatedly operated. In addition, the strong polarization field has an anisotropic control effect on the lattice vibration of black phosphorus, so that the vibration of black phosphorus in the armchair direction is enhanced, which can generate a larger photocurrent, and therefore the polarization detection ratio of the black phosphorus polarized photodetector will be greatly improved.

[0075] Embodiment three

[0076] The embodiment of the present application provides a preparation method of a ferroelectric local field enhanced polarized photodetector, which comprises

[0077] 1. Substrate selection

[0078] A silicon substrate with a silicon dioxide layer (the thickness of which is 285 nanometers) is selected; the thickness of the silicon substrate is 0.3-0.5 millimeters.

[0079] 2. Preparation and transfer of anisotropic two-dimensional semiconductor material (i.e. black phosphorus)

[0080] The bulk material of black phosphorus is mechanically exfoliated in a glove box with a nitrogen atmosphere, and then transferred to the surface of the substrate. In this step, 10 molecular layers of black phosphorus with a thickness of 5 nanometers are selected.

[0081] 3. Preparation of metal source and drain electrodes

[0082] The source-drain metal electrode pattern is prepared by using an electron beam lithography method, and the source-drain metal electrode is prepared by using a thermal evaporation technology (wherein the metal material is chromium and gold; the thickness of the chromium layer is 10 nanometers, the thickness of the gold layer is 20 nanometers, and the gold layer is located on the chromium layer); the metal film is peeled off by using a peeling method, and a metal electrode pair is obtained; wherein the channel width between the two metal electrodes is 5 micrometers.

[0083] 4. Preparation of ferroelectric thin film

[0084] The ferroelectric thin film layer is prepared on the device with the prepared metal electrode pair by using a spin coating method, and then the device is placed in a nitrogen atmosphere glove box, and annealed at 135 DEG C for 2 hours to ensure that the ferroelectric thin film layer has good crystallinity; the thickness of the ferroelectric thin film layer is 50 nanometers.

[0085] 5. Polarization of ferroelectric thin film by using a piezoelectric force microscope

[0086] The device prepared above is placed in a piezoelectric force microscope operating platform, and first, the channel part of the device is scanned by using a probe; the scanning voltage range, electrode polarity and size are set according to the device topography. During the polarization process, the ferroelectric thin film layer corresponding to the left side of the black phosphorus channel is applied with a + 15V scanning voltage, and the right side is applied with a - 15V scanning voltage; the scanning frequency is 2Hz.

[0087] 6. Voltage-current characteristic curve test

[0088] After the two-dimensional semiconductor material, i.e. the black phosphorus, is polarized into an in-plane PN junction, the electrical characteristics are tested in a dark state, the voltage is set to -0.1-0.1V, and the current is tested to obtain the voltage-current characteristic curve; under the illumination of linearly polarized light with a polarization angle of 0 degrees and a wavelength of 1450 nanometers, the voltage-current characteristic curve is obtained again.

[0089] 7. Photocurrent test under polarized light

[0090] The device is placed under linearly polarized light, and the bias voltage is set to 0 volts; the photocurrent under linearly polarized light from 0 degrees to 360 degrees is tested, and the curve of the photocurrent with the change of the polarization angle is obtained; by calculating the ratio of the maximum value (obtained at 0 degrees) and the minimum value (obtained at 90 degrees) of the current, a super-high polarization detection ratio of up to 288 is obtained.

[0091] wherein, Figure 3 is a working condition diagram of the ferroelectric local field enhanced polarized photodetector of the embodiment of the present application under the condition of polarized light illumination, as Figure 3As shown, the polarized light is obtained by converting the natural light into linearly polarized light through a polarizer, and the polarization angle of the polarized light can be adjusted by rotating the half-wave plate. The armchair direction of the anisotropic two-dimensional semiconductor material black phosphorus is defined as 0 degrees, and the zigzag direction is defined as 90 degrees. Under 0 bias, the photoelectric current of the device is obtained by a picoammeter test.

[0092] Embodiment four

[0093] The embodiment of the application develops a ferroelectric local field enhanced polarization photodetector. The anisotropic two-dimensional semiconductor material (i.e. black phosphorus) is regulated by the strong electric field of the ferroelectric local field. Under the action of the strong electric field, the lattice vibration of the black phosphorus in the armchair direction is obviously enhanced, and the photoelectric current is also obviously increased, so that the preparation of the photodetector with high polarization detection ratio is realized.

[0094] The preparation process of the ferroelectric local field enhanced polarization photodetector is as follows:

[0095] 1. Substrate selection

[0096] A silicon substrate with a silicon dioxide layer (the thickness of which is 285 nanometers) is selected; the thickness of the silicon substrate is 0.3-0.5 millimeters.

[0097] 2. Preparation and transfer of two-dimensional semiconductor material (i.e. black phosphorus)

[0098] The bulk material of the black phosphorus is mechanically exfoliated in a glove box with a nitrogen atmosphere, and then transferred to the surface of the substrate. In this step, 20 molecular layers of black phosphorus with a thickness of 10 nanometers are selected.

[0099] 3. Preparation of metal source-drain electrode

[0100] An electron beam lithography method is used to prepare a source-drain metal electrode pattern, and a thermal evaporation technology is used to prepare a source-drain metal electrode (in which the metal material is chromium and gold; the thickness of the chromium layer is 10 nanometers, and the thickness of the gold layer is 20 nanometers, and the gold layer is located on the chromium layer); a metal film is exfoliated by combining an exfoliation method to obtain a metal electrode pair; the channel width between the two metal electrodes is 5 micrometers.

[0101] 4. Preparation of ferroelectric film

[0102] A ferroelectric film layer is prepared on the device with a prepared metal electrode pair by using a spin coating method, and then the device is placed in a nitrogen atmosphere glove box and annealed at 135 DEG C for 3 hours to ensure that the ferroelectric film layer has good crystallinity. The thickness of the ferroelectric film layer is 100 nanometers.

[0103] 5. Polarizing the ferroelectric film by using a piezoelectric force microscope

[0104] Put the above prepared device into the piezoelectric force microscope operation platform, first scan the device channel part through the probe, and set the scanning voltage range, electrode polarity and size according to the device topography. During the polarization process, +20V scanning voltage is applied to the ferroelectric film layer corresponding to the left side of the black phosphorus channel, and -20V scanning voltage is applied to the right side, and the scanning frequency is 2Hz.

[0105] 6. Voltage-current characteristic curve test

[0106] After the two-dimensional semiconductor material, i.e. the polarization of the black phosphorus into the in-plane PN junction, test the electrical characteristics in the dark state, the voltage is set to -0.1-0.1V, and the test current is obtained to obtain the voltage-current characteristic curve; under the illumination of linearly polarized light with a polarization angle of 0 degrees and a wavelength of 1450 nanometers, test again to obtain the voltage-current characteristic curve.

[0107] 7. Photoelectric current test under polarized light

[0108] Place the device under linearly polarized light, and set the bias voltage to 0 volts. Test the photoelectric current under linearly polarized light from 0 degrees to 360 degrees to obtain the curve of photoelectric current with the change of polarization angle. By calculating the ratio of the maximum value (obtained at 0 degrees) and the minimum value (obtained at 90 degrees) of the current, a super-high polarization detection ratio of up to 55 is obtained.

[0109] Example five

[0110] The ferroelectric local field enhanced polarized photodetector is developed in the embodiment of the application. The anisotropic two-dimensional semiconductor material (i.e. black phosphorus) is regulated by using the strong electric field of the ferroelectric local field. Under the action of the strong electric field, the lattice vibration of the black phosphorus in the armchair direction is obviously enhanced, and the photoelectric current is also obviously increased, so that the preparation of the photodetector with high polarization detection ratio is realized.

[0111] The preparation process of the ferroelectric local field enhanced polarized photodetector is as follows:

[0112] 1. Substrate selection

[0113] A silicon substrate with a silicon dioxide layer (the thickness is 285 nanometers) is selected; the thickness of the silicon substrate is 0.3-0.5 millimeters.

[0114] 2. Preparation and transfer of two-dimensional semiconductor material (i.e. black phosphorus)

[0115] In the glove box with a nitrogen atmosphere, the bulk material of black phosphorus is mechanically exfoliated by using adhesive tape, and then transferred to the surface of the substrate. In this step, 30 molecular layers of black phosphorus with a thickness of 15 nanometers are selected.

[0116] 3. Preparation of metal source and drain electrodes

[0117] The source-drain metal electrode pattern is prepared by using an electron beam lithography method, and the source-drain metal electrode is prepared by using a thermal evaporation technology (wherein the metal material is chromium and gold; the thickness of the chromium layer is 10 nanometers, the thickness of the gold layer is 20 nanometers, and the gold layer is located on the chromium layer); the metal film is peeled off by using a peeling method, and a metal electrode pair is obtained; wherein the channel width between the two metal electrodes is 5 micrometers.

[0118] 4. Preparation of ferroelectric thin film

[0119] The ferroelectric thin film layer is prepared on the device with the prepared metal electrode pair by using a spin coating method, and then the device is placed in a nitrogen atmosphere glove box, and annealed at 135 DEG C for 4 hours to ensure that the ferroelectric thin film layer has good crystallinity; the thickness of the ferroelectric thin film layer is 200 nanometers.

[0120] 5. Polarization of ferroelectric thin film by using a piezoelectric force microscope

[0121] The device prepared above is placed in a piezoelectric force microscope operation platform, and first, the channel part of the device is scanned by using a probe; the scanning voltage range, electrode polarity and size are set according to the device topography. During the polarization process, the ferroelectric thin film layer corresponding to the left side of the black phosphorus channel is applied with a +25V scanning voltage, and the right side is applied with a -25V scanning voltage; the scanning frequency is 2Hz.

[0122] 6. Voltage-current characteristic curve test

[0123] After the two-dimensional semiconductor material, i.e. the black phosphorus, is polarized into an in-plane PN junction, the electrical characteristics are tested in a dark state; the voltage is set to -0.1-0.1V, and the current is tested to obtain the voltage-current characteristic curve; the voltage-current characteristic curve is obtained again under the irradiation of linearly polarized light with a polarization angle of 0 degrees and a wavelength of 1450 nanometers.

[0124] 7. Photocurrent test under polarized light

[0125] The device is placed under linearly polarized light, and the bias voltage is set to 0 volt; the photocurrent under the linearly polarized light from 0 degrees to 360 degrees is tested, and the curve of the photocurrent with the change of the polarization angle is obtained; by calculating the ratio of the maximum value (obtained at 0 degrees) and the minimum value (obtained at 90 degrees) of the current, a super-high polarization detection ratio of up to 53 is obtained.

[0126] Figure 4 The current-voltage characteristic curve of the ferroelectric local field enhanced polarized photodetector in the dark state and under irradiation according to the embodiment of the present application is shown in the figure. The current-voltage characteristic curves of the embodiments three to five have little difference, so Figure 4 only the current-voltage characteristic curve of the embodiment three is shown. In Figure 4In the middle: in the dark state, the current value under 0 bias is 0; when the polarization angle is 0 degree, the short-circuit current is 1.58 nanoampere and the open-circuit voltage is 0.016 volt under the irradiation of linearly polarized light with a wavelength of 1450 nanometers.

[0127] Figure 5 The figure is the characteristic curve of the photocurrent of the ferroelectric local field enhanced polarized light photodetector with the change of the polarization angle; in the middle Figure 5 In the middle, the device bias is 0 volt, the irradiation is linearly polarized light with a wavelength of 1450 nanometers and a power of 50 microwatts, and the polarization angle increases from 0 degree to 360 degrees with a step of 15 degrees (the armchair direction is set as 0 degree and the zigzag direction is set as 90 degrees). Among them, Figure 5 (a) is the photocurrent when the thickness of black phosphorus is 5 nanometers and the thickness of the ferroelectric film layer is 50 nanometers; Figure 5 (b) is the photocurrent when the thickness of black phosphorus is 10 nanometers and the thickness of the ferroelectric film layer is 100 nanometers; Figure 5 (c) is the photocurrent when the thickness of black phosphorus is 15 nanometers and the thickness of the ferroelectric film layer is 200 nanometers.

[0128] The application discloses a ferroelectric local field enhanced polarized light photodetector and a preparation method thereof. The polarized light photodetector is sequentially provided with a substrate, a two-dimensional semiconductor layer, a metal electrode pair and a ferroelectric film layer from bottom to top. First, an anisotropic two-dimensional semiconductor material, i.e., black phosphorus, is prepared on the substrate, then a metal electrode pair is prepared by using an electron beam lithography technology in combination with a stripping process, then a ferroelectric film layer is prepared on the structure, and finally the ferroelectric film layer is polarized by using a piezoelectric force microscope technology, so that the left and right sides of the black phosphorus are respectively electron conductive and hole conductive, and finally a polarized light photodetector of a ferroelectric local field regulated black phosphorus in-plane PN junction is formed. Under the action of the ferroelectric field, the thermoelectric efficiency of the black phosphorus is anisotropically enhanced, the built-in electric field of the PN junction accelerates carrier separation, the polarization detection ratio of the polarized light photodetector is significantly improved, the practicability of the device is greatly improved, and the polarized light photodetector has important significance for polarized light detection.

[0129] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the embodiments can be mutually referred to.

[0130] The principles and implementation manners of the application are described by using specific examples in the specification, and the above description of the embodiments is only used to help understand the method of the application and the core idea thereof; meanwhile, according to the idea of the application, the specific implementation manners and application ranges can be changed by those skilled in the art. In conclusion, the content of the specification should not be understood as the limitation of the application.

Claims

1. A polarization photodetector with enhanced ferroelectric localized field, characterized in that, From bottom to top, the layers are: substrate, two-dimensional semiconductor layer, metal electrode pair, and ferroelectric thin film layer. The material of the two-dimensional semiconductor layer is black phosphorus; the material of the ferroelectric thin film layer is polyvinylidene fluoride ferroelectric polymer. The metal electrode pair includes a first metal electrode and a second metal electrode; a channel structure formed between the first metal electrode and the second metal electrode exposes a portion of the two-dimensional semiconductor layer; wherein, by polarizing the ferroelectric thin film layer, the exposed portion of the two-dimensional semiconductor layer forms an in-plane PN junction; The method for fabricating the polarization photodetector includes: transferring two-dimensional semiconductor material to the substrate surface using a mechanical peeling and transfer process in a glove box with a nitrogen atmosphere to generate the two-dimensional semiconductor layer; Using piezoelectric microscopy to polarize the ferroelectric thin film layer in the target sample, thereby forming an in-plane PN junction in the two-dimensional semiconductor layer exposed by the channel structure, specifically including: The conductive probe in the piezoelectric microscope is used to scan the target sample in contact mode to determine the ferroelectric thin film layer; The voltage generated by the signal generator is applied to the ferroelectric thin film layer through the conductive probe. A positive voltage is applied to one side of the ferroelectric thin film layer and a negative voltage is applied to the other side of the ferroelectric thin film layer, thereby controlling the target two-dimensional semiconductor layer to conduct electrons and holes respectively, and finally making the target two-dimensional semiconductor layer form an in-plane PN junction to obtain a polarization photodetector.

2. The polarization photodetector with ferroelectric localized field enhancement according to claim 1, characterized in that, The substrate includes a silicon substrate and a silicon dioxide layer disposed on the silicon substrate; the thickness of the substrate is 0.3-0.5 mm.

3. The polarization photodetector with ferroelectric localized field enhancement according to claim 1, characterized in that, The thickness of the two-dimensional semiconductor layer is 5-15 nanometers, and the thickness of the ferroelectric thin film layer is 50-200 nanometers.

4. A polarization photodetector with ferroelectric localized field enhancement according to claim 1, characterized in that, Both the first metal electrode and the second metal electrode are chromium-gold composite electrodes; the chromium-gold composite electrode includes a chromium layer and a gold layer disposed on the chromium layer; wherein the thickness of the chromium layer is 10 nanometers and the thickness of the gold layer is 20 nanometers.

5. A method for fabricating a polarization photodetector with enhanced ferroelectric localized field, characterized in that, include: A mechanical peel-off transfer process is used to transfer two-dimensional semiconductor material onto a substrate surface to generate a two-dimensional semiconductor layer, specifically including: A two-dimensional semiconductor material is transferred to the substrate surface using a mechanical peeling and transfer process in a glove box with a nitrogen atmosphere to generate a two-dimensional semiconductor layer; the two-dimensional semiconductor material is black phosphorus. A metal electrode pair is fabricated on the two-dimensional semiconductor layer using electron beam lithography, thermal evaporation metal processing, and a lift-off process; the metal electrode pair includes a first metal electrode and a second metal electrode; a channel structure is formed between the first metal electrode and the second metal electrode. A ferroelectric thin film layer was prepared on the target device using a spin coating process to obtain the target sample; the material of the ferroelectric thin film layer is polyvinylidene fluoride ferroelectric polymer; the target device includes the substrate, a two-dimensional semiconductor layer disposed on the substrate, and a metal electrode pair disposed on the two-dimensional semiconductor layer; The ferroelectric thin film layer in the target sample is polarized using a piezoelectric microscope, thereby forming an in-plane PN junction in the two-dimensional semiconductor layer exposed by the channel structure. Specifically, this includes: The target sample is scanned in contact mode using a conductive probe in a piezoelectric microscope to determine the ferroelectric thin film layer; The voltage generated by the signal generator is applied to the ferroelectric thin film layer through a conductive probe. A positive voltage is applied to one side of the ferroelectric thin film layer and a negative voltage is applied to the other side of the ferroelectric thin film layer, thereby controlling the target two-dimensional semiconductor layer to conduct electrons and holes respectively, and finally forming an in-plane PN junction in the target two-dimensional semiconductor layer to obtain a polarization photodetector.

6. The method for fabricating a ferroelectric localized field enhanced polarization photodetector according to claim 5, characterized in that, The method of transferring two-dimensional semiconductor material to the substrate surface using a mechanical peel-off transfer process to generate a two-dimensional semiconductor layer further includes: The substrate includes a silicon substrate and a silicon dioxide layer disposed on the silicon substrate; the thickness of the two-dimensional semiconductor layer is 5-15 nanometers.

7. The method for fabricating a ferroelectric localized field enhanced polarization photodetector according to claim 5, characterized in that, The fabrication of metal electrode pairs on the two-dimensional semiconductor layer using electron beam lithography, thermal evaporation metal processing, and lift-off processes specifically includes: Metal electrode patterns were fabricated on the two-dimensional semiconductor layer using electron beam lithography. The sample metal electrode was prepared on the metal electrode pattern using a thermal evaporation metal process. The metal film on the metal electrode of the sample is peeled off using a stripping process to obtain a metal electrode pair; Wherein, both the first metal electrode and the second metal electrode are chromium-gold composite electrodes; the chromium-gold composite electrode includes a chromium layer and a gold layer disposed on the chromium layer; the thickness of the chromium layer is 10 nanometers and the thickness of the gold layer is 20 nanometers.

8. The method for fabricating a ferroelectric localized field enhanced polarization photodetector according to claim 5, characterized in that, The process of preparing a ferroelectric thin film layer on the target device using spin coating to obtain the target sample specifically includes: In a glove box with a nitrogen atmosphere, a ferroelectric thin film layer was prepared on the target device using a spin coating process to obtain a preliminary target sample; The preliminary target sample is placed on a hot plate and annealed at 135°C for 2-4 hours to obtain the final target sample. The thickness of the ferroelectric thin film layer is 50-200 nanometers.

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