阅读说明：本技术 一种基于铁电pn结的光电器件及其制备方法 (Photoelectric device based on ferroelectric PN junction and preparation method thereof ) 是由 王振兴 王艳荣 王峰 何军 于 2021-08-10 设计创作，主要内容包括：本发明涉及一种基于铁电PN结的光电器件及其制备方法,包括基板；位于所述基板上形成PN结的铁电半导体材料层和光敏材料层,其中所述铁电半导体材料层和与所述光敏材料层在竖直方向上部分重叠并在接触面上形成PN结；第一电极和第二电极,分别与所述铁电半导体材料层和所述光敏材料层电连接。本发明形成的PN结中的铁电半导体材料和光敏材料接触后能够形成内建电势,在施加栅压脉冲后,内建电势能够进行非易失地调控,从而非易失地调控光照下器件的短路电流,进而提高光电器件的效率。(The invention relates to a photoelectric device based on a ferroelectric PN junction and a preparation method thereof, wherein the photoelectric device comprises a substrate; the ferroelectric semiconductor material layer and the photosensitive material layer are positioned on the substrate, and form a PN junction, wherein the ferroelectric semiconductor material layer and the photosensitive material layer are partially overlapped in the vertical direction and form the PN junction on a contact surface; and a first electrode and a second electrode electrically connected to the ferroelectric semiconductor material layer and the photosensitive material layer, respectively. The ferroelectric semiconductor material in the PN junction formed by the invention can form built-in potential after being contacted with the photosensitive material, and the built-in potential can be regulated and controlled in a nonvolatile way after the grid voltage pulse is applied, so that the short-circuit current of the device under illumination can be regulated and controlled in a nonvolatile way, and the efficiency of the photoelectric device is further improved.)

1. An optoelectronic device based on a ferroelectric PN junction, comprising:

a substrate;

the ferroelectric semiconductor material layer and the photosensitive material layer are positioned on the substrate, and form a PN junction, wherein the ferroelectric semiconductor material layer and the photosensitive material layer are partially overlapped in the vertical direction and form the PN junction on a contact surface;

and a first electrode and a second electrode electrically connected to the ferroelectric semiconductor material layer and the photosensitive material layer, respectively.

2. The ferroelectric PN junction-based optoelectronic device of claim 1, the first electrode being located at and electrically connected to an end of the ferroelectric semiconductor material layer not overlapping the photosensitive material layer, and the second electrode being formed at and electrically connected to an end of the photosensitive material layer not overlapping the ferroelectric semiconductor material layer.

3. The ferroelectric PN junction based optoelectronic device of claim 2, the first electrode being formed on the ferroelectric semiconductor material layer, the second electrode being formed on the photosensitive material layer.

4. The ferroelectric PN junction based optoelectronic device of claim 1, which is a diode.

5. The ferroelectric PN junction based optoelectronic device as claimed in claim 1, which is a field effect transistor, wherein a gate of the field effect transistor is formed on the substrate, a drain and a source of the field effect transistor are respectively formed on the first electrode and the second electrode, and the gate is isolated from the ferroelectric semiconductor material layer and the photosensitive material layer by a dielectric layer.

6. The ferroelectric PN junction based optoelectronic device as claimed in claim 1, which is a field effect transistor, wherein a gate of the field effect transistor is formed on the substrate and is isolated from the ferroelectric semiconductor material layer and the photosensitive material layer by a dielectric, and a drain and a source of the field effect transistor are formed on the first electrode and the second electrode, respectively.

7. A rectifier comprising the ferroelectric PN junction based photovoltaic device of claim 1 as a rectifying diode.

8. A preparation method of a photoelectric device based on a ferroelectric PN junction is characterized by comprising the following steps:

providing a substrate;

forming a ferroelectric semiconductor material layer and a photosensitive material layer on the substrate, wherein the ferroelectric semiconductor material layer and the photosensitive material layer partially overlap in a vertical direction and form a PN junction on a contact surface;

forming a first electrode and a second electrode electrically connected to the ferroelectric semiconductor material layer and the photosensitive material layer, respectively.

9. The method of fabricating a ferroelectric PN junction based photovoltaic device as claimed in claim 8, wherein forming a ferroelectric semiconductor material layer and a photosensitive material layer on the substrate comprises:

spin-coating PPC solution on the ferroelectric semiconductor material nano-chip obtained by micro-mechanical stripping;

baking the PPC solution to form a PPC film;

stripping the PPC film adhered with the ferroelectric semiconductor material nanosheets by using deionized water;

transferring the PPC film adhered with the ferroelectric semiconductor material nanosheets onto the nanosheets formed with the photosensitive material layer such that the ferroelectric semiconductor material nanosheets partially cover the nanosheets of the photosensitive material layer;

and dissolving the PPC film to leave the ferroelectric semiconductor material nanosheets to form the ferroelectric semiconductor material layer.

10. A method of fabricating a ferroelectric PN junction based photovoltaic device as in claim 8, wherein forming the first and second electrodes comprises:

forming a photoresist on the ferroelectric semiconductor material layer and the photosensitive material layer;

patterning the photoresist to form a first through hole and a second through hole exposing the ferroelectric semiconductor material layer and the photosensitive material layer;

and filling a conductive material in the first through hole and the second through hole to form a first electrode and a second electrode respectively.

Technical Field

The invention relates to the technical field of inorganic semiconductor nano materials, in particular to a photoelectric device based on a ferroelectric PN junction and a preparation method thereof.

Background

The photoelectric effect is a phenomenon that when light irradiates on the surface of a metal, electrons in the metal can escape from the surface. The photoelectric device refers to a device manufactured according to photoelectric effect, which is called a photoelectric device and is also called a photosensitive device.

Common optoelectronic devices generally include phototubes, photodiodes, phototransistors, etc., and the operation principle of the optoelectronic devices is that when light is irradiated onto the optoelectronic devices, the electrical properties of substances in the optoelectronic devices are changed. The photoelectric device emits the effect of electrons under the irradiation of light, thereby converting optical signals into electrical signals.

However, the optoelectronic devices in the prior art have strong dependence on light and weak current generated under illumination, so the efficiency of converting light into electrical signals is low.

Disclosure of Invention

The invention aims to provide a photoelectric device based on a ferroelectric PN junction and a preparation method thereof, and solves the problem of low efficiency of the photoelectric device in the prior art.

The invention provides a photoelectric device based on a ferroelectric PN junction, which comprises a substrate; the ferroelectric semiconductor material layer and the photosensitive material layer are positioned on the substrate, and form a PN junction, wherein the ferroelectric semiconductor material layer and the photosensitive material layer are partially overlapped in the vertical direction and form the PN junction on a contact surface; and a first electrode and a second electrode electrically connected to the ferroelectric semiconductor material layer and the photosensitive material layer, respectively.

According to the photoelectric device based on the ferroelectric PN junction, the first electrode is positioned at one end, not overlapped with the photosensitive material layer, of the ferroelectric semiconductor material layer and is electrically connected with the ferroelectric semiconductor material layer, and the second electrode is formed at one end, not overlapped with the ferroelectric semiconductor material layer, of the photosensitive material layer and is electrically connected with the photosensitive material layer.

According to the photoelectric device based on the ferroelectric PN junction, the first electrode is formed on the ferroelectric semiconductor material layer, and the second electrode is formed on the photosensitive material layer.

According to the photoelectric device based on the ferroelectric PN junction, the photoelectric device is a diode.

According to the photoelectric device based on the ferroelectric PN junction, the photoelectric device is a field effect transistor, a grid electrode of the field effect transistor is formed on the substrate, a drain electrode and a source electrode of the field effect transistor are respectively formed on the first electrode and the second electrode, and the grid electrode, the ferroelectric semiconductor material layer and the photosensitive material layer are arranged in an isolated mode through the dielectric layer.

According to the photoelectric device based on the ferroelectric PN junction, the photoelectric device is a field effect transistor, the grid electrode of the field effect transistor is formed on the substrate and is isolated from the ferroelectric semiconductor material layer and the photosensitive material layer through a medium, and the drain electrode and the source electrode of the field effect transistor are respectively formed on the first electrode and the second electrode.

The invention also provides a rectifier comprising a ferroelectric PN junction based photovoltaic device, said photovoltaic device acting as a rectifying diode.

The invention also provides a preparation method of the photoelectric device based on the ferroelectric PN junction, which is characterized by comprising the following steps: providing a substrate; forming a ferroelectric semiconductor material layer and a photosensitive material layer on the substrate, wherein the ferroelectric semiconductor material layer and the photosensitive material layer partially overlap in a vertical direction and form a PN junction on a contact surface; forming a first electrode and a second electrode electrically connected to the ferroelectric semiconductor material layer and the photosensitive material layer, respectively.

According to the preparation method of the photoelectric device based on the ferroelectric PN junction, which is provided by the invention, the ferroelectric semiconductor material layer and the photosensitive material layer are formed on the substrate, and the preparation method comprises the following steps: spin-coating PPC solution on the ferroelectric semiconductor material nano-chip obtained by micro-mechanical stripping; baking the PPC solution to form a PPC film; stripping the PPC film adhered with the ferroelectric semiconductor material nanosheets by using deionized water; transferring the PPC film adhered with the ferroelectric semiconductor material nanosheets onto the nanosheets formed with the photosensitive material layer such that the ferroelectric semiconductor material nanosheets partially cover the nanosheets of the photosensitive material layer; and dissolving the PPC film to leave the ferroelectric semiconductor material nanosheets to form the ferroelectric semiconductor material layer.

According to the preparation method of the photoelectric device based on the ferroelectric PN junction, the first electrode and the second electrode are formed, and the preparation method comprises the following steps: forming a photoresist on the ferroelectric semiconductor material layer and the photosensitive material layer; patterning the photoresist to form a first through hole and a second through hole exposing the ferroelectric semiconductor material layer and the photosensitive material layer; and filling a conductive material in the first through hole and the second through hole to form a first electrode and a second electrode respectively.

The invention provides a photoelectric device based on a ferroelectric PN junction and a preparation method thereof, wherein the photoelectric device based on the ferroelectric PN junction can comprise a ferroelectric semiconductor material layer and a photosensitive material layer which are positioned on a substrate and form the PN junction, wherein the ferroelectric semiconductor material layer and the photosensitive material layer are partially overlapped in the vertical direction and form the PN junction on a contact surface. Since the ferroelectric semiconductor material layer has a non-volatile ferroelectric polarization, a controllable depolarization field can be maintained in the ferroelectric semiconductor material layer for a certain period of time without applying a driving voltage. Under the condition, the internal potential of the ferroelectric material layer can be adjusted by applying illumination to the photoelectric device, so that the output current of the photoelectric device can be adjusted, the optical device shows a nonvolatile and adjustable photovoltaic effect and photoelectric conversion efficiency under the condition of not applying driving voltage, and the photoelectric conversion efficiency is improved.

Drawings

FIG. 1 is a schematic structural diagram of a ferroelectric PN junction-based optoelectronic device provided by the present invention;

FIG. 2 is one of the effect diagrams of the photoelectric device based on the ferroelectric PN junction provided by the present invention as a photodiode;

FIG. 3 is a second diagram illustrating the effect of the present invention in which a photoelectric device based on a ferroelectric PN junction is a photodiode;

fig. 4 is a third effect diagram of the photoelectric device based on the ferroelectric PN junction provided by the present invention as a photodiode;

FIG. 5 is a fourth diagram illustrating the effect of the photoelectric device based on the ferroelectric PN junction as a photodiode according to the present invention;

FIG. 6 is a structural diagram of a field effect transistor based on a ferroelectric PN junction provided by the present invention;

FIG. 7 is a schematic structural diagram of a photoelectric device based on a ferroelectric PN junction according to the present invention, which is a field effect transistor as a retina-like synapse;

FIG. 8 is a diagram illustrating the effect of a ferroelectric PN junction-based optoelectronic device as a field effect transistor as a retina-like synapse according to the present invention;

FIG. 9 is a second diagram illustrating the effect of a ferroelectric PN junction-based optoelectronic device of the present invention as a field effect transistor as a retinal-like synapse;

FIG. 10 is a third diagram illustrating the effect of a ferroelectric PN junction-based optoelectronic device of the present invention as a field effect transistor as a retinal-like synapse;

FIG. 11 is one of the effect diagrams of the rectifier of a photoelectric device based on a ferroelectric PN junction provided by the present invention;

fig. 12 is a second effect diagram of the rectifier of the present invention based on a ferroelectric PN junction photoelectric device;

fig. 13 is one of the flow charts of the method for manufacturing a photoelectric device based on a ferroelectric PN junction provided by the present invention;

fig. 14 is a second flowchart of a method for manufacturing a photovoltaic device based on a ferroelectric PN junction according to the present invention;

fig. 15 is a third flow chart of a method for manufacturing a photoelectric device based on a ferroelectric PN junction according to the present invention.

In the figure: 1. a substrate; 2. a layer of ferroelectric semiconductor material; 3. a photosensitive material layer; 4. a first electrode; 5. a second electrode; 6. a gate electrode; 7. a source electrode; 8. a drain electrode; 9. a dielectric layer.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The invention provides a photoelectric device based on a ferroelectric PN junction, which comprises a substrate 1; a ferroelectric semiconductor material layer 2 and a photosensitive material layer 3 which are positioned on the substrate 1 to form a PN junction, wherein the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 are partially overlapped in the vertical direction and form a PN junction on a contact surface; a first electrode 4 and a second electrode 5 electrically connected to the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3, respectively.

Specifically, the substrate 1 is located at the bottom of the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3, and functions as a support. The substrate 1 is made of a semiconductor material, and silicon or germanium is generally used. A dielectric layer 9 is further arranged between the substrate 1 and the layer of ferroelectric semiconductor material 2 and the layer of photosensitive material 3, the dielectric layer 9 being made of an insulator, typically silicon dioxide. A ferroelectric semiconductor material layer 2 and a photosensitive material layer 3 are located on a substrate 1, and both form an N-type region and a P-type region, respectively, to form a heterojunction. The ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 are partially overlapped in the vertical direction to form a PN junction. The first electrode 4 and the second electrode 5 are two electrical connection ports of the photoelectric device, and are respectively used for being connected with a negative electrode and a positive electrode of a power supply, so that the unidirectional conductivity of the photoelectric device is exerted.

Further, the first electrode 4 is located at an end of the ferroelectric semiconductor material layer 2 not overlapping with the photosensitive material layer 3 and is electrically connected to the ferroelectric semiconductor material layer 2, and the second electrode 5 is formed at an end of the photosensitive material layer 3 not overlapping with the ferroelectric semiconductor material layer 2 and is electrically connected to the photosensitive material layer 3.

The first electrode 4 is formed on the ferroelectric semiconductor material layer 2, and the second electrode 5 is formed on the photosensitive material layer 3.

Specifically, the first electrode 4 and the second electrode 5 are provided on the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3, respectively, and are located at both ends of both. In other embodiments, the first electrode and the second electrode may be disposed on the side surfaces of the ferroelectric semiconductor material layer and the photosensitive material layer (not shown).

The ferroelectric semiconductor material layer 2 is made of a ferroelectric semiconductor material, the ferroelectric semiconductor material is a material having both ferroelectric effect and semiconductor characteristics, the ferroelectric semiconductor material has ferroelectricity, in the crystal of the ferroelectric material, the electric dipole moment appears due to the misalignment of the positive and negative charge centers due to the structure of the unit cell, electric polarization strength which is not equal to zero is generated, the crystal has spontaneous polarization, and the direction of the electric dipole moment can be changed due to an external electric field, thus presenting the characteristic similar to a ferromagnet. The ferroelectric material is polarized by applying an external voltage, and after the external voltage is removed, electric dipoles in the ferroelectric material are arranged in order to generate a huge depolarization electric field. In the embodiment, the ferroelectric semiconductor material is combined with another photosensitive material, and the internal characteristics of the PN junction are regulated by using a strong local electric field generated by the remnant polarization of the ferroelectric semiconductor material.

In the embodiment, the ferroelectric semiconductor material layer 2 is indium selenide, and indium selenide has better conductivity compared with silicon. Indium selenide, which is a ferroelectric material, can generate a depolarization field according to its own spontaneous polarization, and has a narrow band gap, and thus can absorb light more effectively, thereby generating a larger current in a circuit.

In this embodiment, the photosensitive material layer 3 is made of molybdenum ditelluride, which has better conductivity than silicon. The Fermi level of the molybdenum ditelluride is matched with that of the indium selenide, and after the Fermi level of the molybdenum ditelluride and the indium selenide form a PN junction, the molybdenum ditelluride can enable the ferroelectric polarization of the indium selenide to better adjust the size of the built-in potential. The ferroelectric semiconductor material has a narrow band gap, so that stronger current can be generated under the illumination condition, and the photoelectric effect efficiency is improved. In other embodiments, molybdenum ditelluride may also be replaced with tungsten diselenide, black phosphorus, and the like.

In an alternative embodiment, the optoelectronic device is a diode.

When the diode in this embodiment is a photodiode, the PN junction in the photodiode has better performance due to its special material. The concrete expression is as follows: since the ferroelectric semiconductor material layer 2 has a non-volatile ferroelectric polarization, this enables a controllable depolarization field to be maintained within the ferroelectric semiconductor material layer 2 for a certain period of time without application of a driving voltage. Under the condition, the built-in potential of the PN junction can be adjusted by applying illumination to the photoelectric device, so that the output current of the photoelectric device can be adjusted, the optical device shows a nonvolatile and adjustable photovoltaic effect and photoelectric conversion efficiency under the condition of not applying driving voltage, and the photoelectric conversion efficiency is improved. Under the illumination condition, the ferroelectric semiconductor material layer 2 forms a depolarization field due to the ferroelectric polarization thereof, and the photosensitive material layer 3 forming a PN junction with the ferroelectric semiconductor material layer 2 can enable the ferroelectric polarization of the ferroelectric semiconductor material layer 2 to better adjust the magnitude of the built-in potential due to the Fermi level matching with the ferroelectric semiconductor material layer 2. The ferroelectric material has a narrow band gap, so that under the condition of illumination, larger current can be generated. Therefore, the photodiode provided by the invention can enhance the photoelectric effect efficiency and generate larger current, so that larger power supply voltage does not need to be added, and the energy consumption is reduced.

This example, when used as a photodiode, shows the photoelectric effect curves in the initial state of indium selenide and in both polarization states, polarization up and polarization down. As shown in fig. 2-5, the photoelectric effect of different polarization states under the irradiation of laser light at 473 nm, 539 nm, 639 nm and 808 nm is shown. As can be seen from fig. 2 to 5, the current is zero in the dark state when no voltage is applied, and the increase and decrease of the current are significantly changed from the original state when a forward or reverse voltage is applied. The concrete expression is as follows: in an original state, when illumination is applied, the output current is in direct proportion to the voltage, and the current is increased along with the increase of the voltage; after the 80-Ford pulse is applied, the magnitude of the increase in current increases; after-80 Ford pulses are applied, the magnitude of the increase in current is reduced. And, when the laser irradiation is 539 nm, the current increasing effect is most obvious, and when the laser irradiation is 808 nm, the current increasing amplitude is weakened. Therefore, the photodiode of the present embodiment has a significant modulation behavior for the photoelectric effect.

In a preferred embodiment, the optoelectronic device based on the ferroelectric PN junction is a field effect transistor, a gate 6 of the field effect transistor is formed on the substrate 1, a drain 8 and a source 7 of the field effect transistor are respectively formed on the first electrode 4 and the second electrode 5, and the gate 6 is isolated from the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 by a dielectric layer 9.

Specifically, the substrate 1 is located at the bottom, and functions as a support, and the substrate 1 itself may function as a gate electrode. A dielectric layer 9, typically made of an insulating material, is located over the substrate 1 for isolating the gate 6 from the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3. In the present embodiment, the conductive channel of the field effect transistor is formed by connecting the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 in series.

In an alternative embodiment, the optoelectronic device based on the ferroelectric PN junction is a field effect transistor, the gate 6 of the field effect transistor is formed on the substrate 1 and is isolated from the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 by a medium, and the drain 8 and the source 7 of the field effect transistor are respectively formed on the first electrode 4 and the second electrode 5.

As shown in fig. 6, specifically, the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 are disposed on the substrate 1, the dielectric layer 9 is disposed on the PN junction formed by the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3, and the gate electrode 6 is formed on the dielectric layer 9. The source electrode 7 and the drain electrode 8 are respectively disposed on the photosensitive material layer 3 and on the ferroelectric semiconductor material layer 2.

When the photoelectric device is used as a field effect transistor, when a voltage is applied to the grid 6, the polarization of the ferroelectric semiconductor material layer 2 can be adjusted, a depolarization field is generated, and the magnitude of the built-in potential is adjusted, and the photosensitive material layer 3 and the ferroelectric semiconductor material layer 2 have matched Fermi energy levels, so that the depolarization field generated by the polarization in the ferroelectric semiconductor material layer can better adjust the built-in potential of a PN junction.

Specifically, in the field effect transistor access circuit provided by the invention, the gate 6 is connected with a pulse voltage, so that a depolarization field is generated inside the ferroelectric semiconductor material layer 2. When the depolarization field and the built-in potential formed by the PN junction are in the same direction, stronger short-circuit current can be generated; when the depolarization field is opposite to the built-in potential direction formed by the PN junction, the short-circuit current can be restrained, and the circuit is cut off.

As shown in fig. 7 and 8, the field effect transistor provided in this embodiment can be used as a synaptic structure of retina, and the post-synaptic neuron 11 can amplify the enhancing and inhibiting effects of the pre-synaptic neuron 10, resulting in a stronger enhancing or inhibiting response.

Specifically, the source and the drain of the field effect transistor are connected, short-circuit current can be generated under the illumination condition, and the increase and the decrease of the short-circuit current can be realized through the positive and negative amplitudes of the gate voltage. The enhancement and inhibition of biological neurosynaptic weights are simulated by the ability of the fet to increase and decrease current in this embodiment.

As shown in FIG. 9, the field effect transistor provided in this embodiment can be used as a retinal-like optoelectronic synapse device to simulate the dipulse facilitation and dipulse inhibition behavior of a neurosynaptic. When the frequency of applied pulses is higher, the short-circuit current is obviously enhanced, and the double-pulse facilitation action of corresponding nerve synapses is realized; when the applied pulse frequency is lower, the short circuit current decreases significantly, corresponding to the dipulse inhibition behavior of the neurosynaptic.

As shown in fig. 10, the field effect transistor provided in this embodiment can be used as a synaptic structure similar to retina to simulate the neural morphology learning rule. Only 60 pulse stimuli are needed for the second learning, and only 25 pulse stimuli are needed for the third learning, relative to the learning intensity achieved by the first 100 pulse stimuli.

The invention provides a rectifier, which comprises a photoelectric device based on a ferroelectric PN junction, wherein the photoelectric device is used as a rectifying diode.

The rectifier is a device for converting alternating current into direct current, and the working principle of the rectifier is as follows: the PN junction has a large current when forward biased and a small current when reverse biased. The rectification ratio is a ratio of a magnitude of a current when the current is applied in a forward direction to a magnitude of a current when the current is turned off in a reverse direction.

As shown in fig. 11 and 12, when the positive and negative pulse voltages are applied, the PN junction in the rectifier can further enhance the current amplification and attenuation due to the depolarization field formed by the ferroelectric semiconductor material layer 2. Specifically, when the pulse voltage is the same as the built-in potential direction formed by the PN junction of the ferroelectric semiconductor material layer, stronger current can be generated; when the pulse voltage is opposite to the built-in potential direction formed by the PN junction of the ferroelectric semiconductor material layer, the PN junction in the rectifier forms an open circuit, and therefore the circuit is cut off. Since the rectifier provides an enhancement to both the increase and decrease in current, a greater rectification ratio can be produced when a pulsed voltage is applied.

The invention provides a preparation method of a photoelectric device based on a ferroelectric PN junction, which comprises the following steps as shown in FIG. 13:

s1: providing a substrate 1;

specifically, the substrate 1 is made of a semiconductor material, and a dielectric layer 9 for insulation is further disposed on the substrate 1.

S2: forming a ferroelectric semiconductor material layer 2 and a photosensitive material layer 3 on the substrate 1, wherein the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 partially overlap in a vertical direction and form a PN junction on a contact surface;

s3: a first electrode 4 and a second electrode 5 are formed, the first electrode 4 and the second electrode 5 being electrically connected to the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3, respectively.

Further, as shown in fig. 14, forming a ferroelectric semiconductor material layer 2 and a photosensitive material layer 3 on the substrate 1 includes:

s21: spin-coating PPC solution on the ferroelectric semiconductor material nano-chip obtained by micro-mechanical stripping;

s22: baking the PPC solution to form a PPC film;

s23: stripping the PPC film adhered with the ferroelectric semiconductor material nanosheets by using deionized water;

s24: transferring the PPC film adhered with the ferroelectric semiconductor material nanosheets onto the nanosheets formed with the photosensitive material layer 3 such that the ferroelectric semiconductor material nanosheets partially cover the nanosheets of the photosensitive material layer 3;

s25: the PPC film is dissolved leaving the ferroelectric semiconductor material nanoplates forming the ferroelectric semiconductor material layer 2.

Specifically, the ferroelectric semiconductor material nanosheet is an indium selenide nanosheet, and the nanosheet of the photosensitive material layer 3 is a molybdenum ditelluride nanosheet. The two types of nanosheets are prepared by folding and pasting corresponding block materials through transparent adhesive tapes, putting molybdenum ditelluride nanosheets and indium selenide nanosheets on a substrate 1 with a 300-nanometer thick silicon dioxide oxide layer, spin-coating a PPC solution on a silicon substrate with the indium selenide nanosheets, and stripping the indium selenide nanosheets from the silicon substrate under the support of a plastic frame after drying the PPC solution. The indium selenide nanosheets are stripped from the silicon substrate, and the indium selenide nanosheets are required to be accurately placed on the molybdenum ditelluride nanosheets with the help of an optical microscope.

Further, as shown in fig. 15, forming the first electrode 4 and the second electrode 5 includes:

s31: forming a photoresist on the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3;

s32: patterning the photoresist to form a first through hole and a second through hole exposing the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3;

s33: and filling a conductive material in the first through hole and the second through hole to form a first electrode 4 and a second electrode 5 respectively.

Specifically, after spin-coating a photoresist, a first through hole and a second through hole are formed on the photoresist by electron beam exposure, and the ferroelectric semiconductor material layer 2 and the photosensitive material layer 3 are exposed through the first through hole and the second through hole. Two metal electrodes are then formed in the first and second vias by depositing metal. Wherein, the metal electrode is made of gold and chromium, and the thicknesses of the gold and the chromium are respectively 60 nanometers and 8 nanometers.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.