A piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction and its preparation method and application

Abstract

The present invention discloses a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, and its preparation method and application, belonging to the technical field of sensor instrument construction. The present invention uses an In2Se3 / InSe vertical heterojunction thin film as a pressure-sensitive layer to prepare a piezoelectric pressure sensor. The stress change caused by the air pressure will change the energy band structure of the In2Se3 / InSe vertical heterojunction, thereby generating a piezoelectric voltage. This change can be monitored by detecting its voltage change through a charge amplifier, thereby achieving a highly sensitive response to tiny air pressure changes. The piezoelectric pressure sensor of the present invention is small in size and highly sensitive, providing a simple, sensitive and stable device and detection method for high-precision air pressure detection.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor instrument construction, and in particular to a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, and a preparation method and application thereof. Background Art

[0002] Barometric pressure sensors are primarily used in weather forecasting, altitude measurement, autonomous vehicles, drones, smart homes, industrial automation, the Internet of Things (IoT), aerospace, and smart wearables. A typical barometric pressure sensor consists of a sensitive element that strains with changes in pressure. This strain response results in changes in the sensor's resistance or capacitance. The rapid development of the IoT, aerospace, and smart wearables is placing higher demands on barometric pressure sensors, requiring continuous miniaturization of both device and package size while maintaining high accuracy and robust stability. This conflict between miniaturization and high precision has led to the emergence and development of barometric pressure sensors based on two-dimensional materials. These sensors utilize two-dimensional materials as the sensing structure and are primarily based on electrical transconductance and piezoresistivity readings. Both rely on changes in membrane conductance with membrane deflection, using this change to sense membrane motion and subsequently convert it into pressure. However, barometric pressure sensors based on these two detection principles suffer from the need for external power, slow response times, low sensitivity, and low accuracy. Therefore, the development of high-performance barometric pressure sensors based on novel detection principles is crucial. Summary of the Invention

[0003] The purpose of the present invention is to provide a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, and its preparation method and application, in order to solve the problems existing in the above-mentioned prior art. The present invention prepares a piezoelectric pressure sensor using an In2Se3 / InSe vertical heterojunction thin film as a pressure-sensitive layer. The stress change caused by the air pressure will change the energy band structure of the In2Se3 / InSe vertical heterojunction, thereby generating a piezoelectric voltage. This change can be monitored by detecting its voltage change through a charge amplifier, thereby achieving a highly sensitive response to tiny air pressure changes. The piezoelectric pressure sensor of the present invention is small in size and highly sensitive, providing a simple, sensitive and stable device and detection method for high-precision air pressure detection.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention: A piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, comprising a first electrical insulating layer, a substrate, a second electrical insulating layer, a bottom electrode, a pressure-sensitive layer, and a top electrode; wherein the first electrical insulating layer and the second electrical insulating layer are respectively arranged on both sides of the substrate, and the bottom electrode is embedded in the upper surface of the second electrical insulating layer; the pressure-sensitive layer is arranged on the upper surfaces of the bottom electrode and the second electrical insulating layer, and the top electrode is arranged on the upper surface of the pressure-sensitive layer;

[0006] The pressure sensitive layer is an In2Se3 / InSe vertical heterojunction film;

[0007] The substrate and the second electrical insulating layer are provided with penetrating micro-nanoscale arrayed cavities.

[0008] Furthermore, the In2Se3 / InSe vertical heterojunction thin film includes an In2Se3 layer and an InSe layer. The InSe layer is disposed on the upper surface of the bottom electrode and the second electrically insulating layer (the InSe layer contacts the bottom electrode), and the In2Se3 layer partially overlaps or completely covers the upper surface of the InSe layer (the In2Se3 layer contacts the top electrode). The thickness of the In2Se3 layer is 1-10 nm, and the thickness of the InSe layer is 0.7-10 nm. The vertical heterojunction formed by the In2Se3 layer and the InSe layer (with a lattice constant close to that of In2Se3) is specifically a two-dimensional vertical van der Waals heterojunction.

[0009] Furthermore, the piezoelectric air pressure sensor further includes a side electrode located on a side of the air pressure sensitive layer.

[0010] Furthermore, the side electrode covers the outer edge of the pressure sensitive layer.

[0011] Furthermore, the shape of the side electrode includes C-type or Π-type.

[0012] Furthermore, when the In2Se3 layer is partially overlapped with the upper surface of the InSe layer, the In2Se3 / InSe vertical heterojunction film is a double-layer overlapped structure, that is, it can be divided into three parts in the horizontal direction: a part with only InSe, a part with only In2Se3, and a part where In2Se3 and InSe overlap to form a vertical heterojunction. The side electrode is located on the side of the In2Se3 part, covering the outer edge of the In2Se3 part. The side electrode fully covers the vertical direction and extends horizontally to cover 30-50% of the horizontal length of the In2Se3 / InSe vertical heterojunction film. The part where In2Se3 and InSe overlap to form a vertical heterojunction completely covers the micro-nanoscale arrayed cavities on the substrate and the second electrical insulating layer, forming a cavity isolated from the external atmospheric pressure (a closed absolute pressure cavity);

[0013] When the In2Se3 layer completely covers the upper surface of the InSe layer, the In2Se3 / InSe vertical heterojunction film has a double-layer covering structure. The side electrode is located on one side of the In2Se3 / InSe vertical heterojunction film, covering the outer edge of the In2Se3 / InSe vertical heterojunction film. The side electrode completely covers the vertical direction and extends horizontally to cover 30-50% of the horizontal length of the In2Se3 / InSe vertical heterojunction film. The In2Se3 / InSe vertical heterojunction film completely covers the micro-nanoscale arrayed cavities on the substrate and the second electrically insulating layer, forming a cavity isolated from the external atmospheric pressure.

[0014] Furthermore, the substrate is a silicon wafer; the second electrical insulating layer is made of silicon dioxide with a thickness of 200-1000 nm.

[0015] Furthermore, the hole shape of the micro-nanoscale arrayed cavity is circular, square or rectangular; the arrangement of the micro-nanoscale arrayed cavity includes parallel arrangement or hexagonal arrangement; the hole center spacing of the micro-nanoscale arrayed cavity is 6-20 μm.

[0016] Furthermore, when the hole shape of the micro-nanoscale arrayed cavity is circular, the hole radius is 3-20 μm; when the hole shape of the micro-nanoscale arrayed cavity is square or rectangular, the hole side length is 3-20 μm.

[0017] Furthermore, the number of the micro-nanoscale arrayed cavities is 16.

[0018] Furthermore, the top electrode is made of gold, platinum, nickel, silver paste or conductive polymer; the bottom electrode is made of gold, platinum, nickel, silver paste or conductive polymer; and the side electrodes are made of gold, platinum, nickel, silver paste or conductive polymer.

[0019] Furthermore, the first insulating layer is made of silicon nitride, mica or polymer.

[0020] Furthermore, the thickness of the substrate is 300-2000 μm, the thickness of the bottom electrode is 10-130 nm, the thickness of the top electrode layer is 10-200 nm, the thickness of the first insulating layer is 209-300 nm, and the thickness of the side electrode is 5-20 nm.

[0021] Technical solution 2 of the present invention: The method for preparing the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction comprises the following steps:

[0022] A first electrical insulating layer is formed on the lower surface of the substrate, and a second electrical insulating layer is formed on the upper surface of the substrate;

[0023] Spin-coating photoresist on the surface of the second electrical insulating layer, patterning it by photolithography, and then forming micro-nanoscale arrayed cavities penetrating the second electrical insulating layer and the substrate by dry etching;

[0024] forming a bottom electrode on the second electrical insulating layer by photolithography and magnetron sputtering;

[0025] By layer-by-layer transfer, an In2Se3 / InSe vertical heterojunction film is prepared on the surface of the second electrical insulating layer after the micro-nanoscale arrayed cavities are formed and the bottom electrode is prepared;

[0026] A top electrode is prepared on the surface of the In2Se3 / InSe vertical heterojunction film, and a side electrode is prepared on the side by photolithography and magnetron sputtering, thereby obtaining the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction.

[0027] Furthermore, the layer-by-layer transfer method specifically includes tungsten steel probe transfer, thermal release tape assisted dry transfer, polymethyl methacrylate assisted wet transfer or water droplet assisted wet transfer.

[0028] The third technical solution of the present invention: Application of the above-mentioned piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction in high-precision pressure detection.

[0029] The present invention discloses the following technical effects:

[0030] (1) The pressure sensor of the present invention, when in use, actually follows the piezoelectric pressure detection principle based on the In2Se3 / InSe vertical heterojunction, which is novel and advanced. The out-of-plane piezoelectric properties of the In2Se3 / InSe heterojunction can be significantly controlled by strain, greatly improving the sensitivity of pressure detection. The present invention fully utilizes the high carrier mobility of In2Se3 and InSe to improve the response speed of the sensor. The pressure sensor of the present invention responds sensitively to small changes in pressure.

[0031] (2) Compared with existing pressure sensors based on two-dimensional piezoelectric materials, the present invention introduces a side electrode design. The side electrode can be connected to the top electrode as an auxiliary electrode to enhance the collection of charges escaping from the side of the In2Se3 material. This creates a larger effective electrode area and increases the sensitivity of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 Schematic cross-sectional view of a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction according to the present invention;

[0034] Figure 2 1 is a top view of the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction of the present invention;

[0035] Figure 3 Schematic diagram of the working principle of the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction of the present invention;

[0036] Figure 4 Schematic diagram of the charge spatial distribution of In2Se3 / InSe heterojunction;

[0037] Figure 5 This is the output curve of the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction prepared in Example 1;

[0038] Figure 6 The corresponding relationship between air pressure and voltage of the piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0042] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0043] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0044] like Figure 1 (Schematic diagram of a cross-section of an air pressure sensor) and Figure 2 As shown in FIG5 (top view of pressure sensor), the present invention provides a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, comprising a first electrically insulating layer, a substrate, a second electrically insulating layer, a bottom electrode, a pressure-sensitive layer, and a top electrode; wherein the first electrically insulating layer and the second electrically insulating layer are respectively arranged on both sides of the substrate, and the bottom electrode is embedded in the upper surface of the second electrically insulating layer; the pressure-sensitive layer is arranged on the upper surfaces of the bottom electrode and the second electrically insulating layer, and the top electrode is arranged on the upper surface of the pressure-sensitive layer;

[0045] The pressure-sensitive layer is an In2Se3 / InSe vertical heterojunction thin film, including an In2Se3 layer and an InSe layer. The InSe layer is arranged on the upper surface of the bottom electrode and the second electrical insulating layer (InSe contacts the bottom electrode), and the In2Se3 layer partially overlaps the upper surface of the InSe layer or completely covers the upper surface of the InSe layer (In2Se3 contacts the top electrode).

[0046] The substrate and the second electrical insulating layer are provided with penetrating micro-nanoscale arrayed cavities;

[0047] The piezoelectric air pressure sensor further includes a side electrode located on a side of the air pressure sensitive layer, wherein the side electrode covers an outer edge of the air pressure sensitive layer;

[0048] When the In2Se3 layer partially overlaps the upper surface of the InSe layer ( Figure 1 and Figure 2 Only a partial overlap is shown in the figure). The In2Se3 / InSe vertical heterojunction film has a double-layer overlap structure, that is, it can be divided into three parts in the horizontal direction: a part with only InSe, a part with only In2Se3, and a part where In2Se3 and InSe overlap to form a vertical heterojunction. The side electrode is located on the side of the In2Se3 part, covering the outer edge of the In2Se3 part. The side electrode fully covers the vertical direction and extends in the horizontal direction to 30-50% of the horizontal length of the In2Se3 / InSe vertical heterojunction film. The part where In2Se3 and InSe overlap to form a vertical heterojunction completely covers the micro-nanoscale arrayed cavities on the substrate and the second electrical insulating layer, forming a cavity isolated from the external atmospheric pressure (a closed absolute pressure cavity);

[0049] When the In2Se3 layer completely covers the upper surface of the InSe layer, the In2Se3 / InSe vertical heterojunction film has a double-layer covering structure. The side electrode is located on one side of the In2Se3 / InSe vertical heterojunction film, covering the outer edge of the In2Se3 / InSe vertical heterojunction film. The side electrode completely covers the vertical direction and extends horizontally to cover 30-50% of the horizontal length of the In2Se3 / InSe vertical heterojunction film. The In2Se3 / InSe vertical heterojunction film completely covers the micro-nanoscale arrayed cavities on the substrate and the second electrically insulating layer, forming a cavity isolated from the external atmospheric pressure.

[0050] As a preferred embodiment of the present invention, the shape of the side electrode includes C-type or Π-type ( Figure 1 and Figure 2 Only the π type is shown).

[0051] As a preferred embodiment of the present invention, the thickness of the In2Se3 layer is 1-10 nm, and the thickness of the InSe layer is 0.7-10 nm.

[0052] As a preferred embodiment of the present invention, the substrate is a silicon wafer (Si); the second electrical insulating layer is made of silicon dioxide (SiO2) with a thickness of 200-1000 nm.

[0053] As a preferred embodiment of the present invention, the shape of the micro-nanoscale arrayed cavity is circular, square or rectangular ( Figure 1 and Figure 2 Only the circular case is shown); the arrangement of the micro-nanoscale arrayed cavities includes parallel arrangement or hexagonal arrangement ( Figure 1 and Figure 2 Only the parallel arrangement is shown); the center-to-center spacing of the micro-nanoscale arrayed cavities is 6-20 μm.

[0054] As a preferred embodiment of the present invention, when the hole shape of the micro-nanoscale arrayed cavity is circular, the hole radius is 3-20 μm; when the hole shape of the micro-nanoscale arrayed cavity is square or rectangular, the hole side length is 3-20 μm.

[0055] As a preferred embodiment of the present invention, the number of the micro-nanoscale arrayed cavities is 16.

[0056] As a preferred embodiment of the present invention, the top electrode is made of gold, platinum, nickel, silver paste or conductive polymer; the bottom electrode is made of gold, platinum, nickel, silver paste or conductive polymer; and the side electrode is made of gold, platinum, nickel, silver paste or conductive polymer.

[0057] As a preferred embodiment of the present invention, the first insulating layer is made of silicon nitride (Si3N4), mica or polymer ( Figure 1 Only the case with silicon nitride is shown).

[0058] As a preferred embodiment of the present invention, the thickness of the substrate is 300-2000 μm, the thickness of the bottom electrode is 10-130 nm, the thickness of the top electrode layer is 10-200 nm, the thickness of the first insulating layer is 209-300 nm, and the thickness of the side electrode is 5-20 nm.

[0059] The present invention also provides a method for preparing the above-mentioned piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction, comprising the following steps:

[0060] A first electrical insulating layer is formed on the lower surface of the substrate, and a second electrical insulating layer is formed on the upper surface of the substrate;

[0061] Spin-coating photoresist on the surface of the second electrical insulating layer, patterning it by photolithography, and then forming micro-nanoscale arrayed cavities penetrating the second electrical insulating layer and the substrate by dry etching;

[0062] forming a bottom electrode on the second electrical insulating layer by photolithography and magnetron sputtering;

[0063] By layer-by-layer transfer, an In2Se3 / InSe vertical heterojunction film is prepared on the surface of the second electrical insulating layer after the micro-nanoscale arrayed cavities are formed and the bottom electrode is prepared;

[0064] A top electrode is prepared on the surface of the In2Se3 / InSe vertical heterojunction film, and a side electrode is prepared on the side by photolithography and magnetron sputtering, thereby obtaining the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction.

[0065] As a preferred embodiment of the present invention, the layer-by-layer transfer method specifically includes tungsten steel probe transfer, thermal release tape assisted dry transfer, polymethyl methacrylate assisted wet transfer or water droplet assisted wet transfer.

[0066] The present invention also provides an application of the above-mentioned piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction in high-precision pressure detection.

[0067] The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction of the present invention uses an In2Se3 / InSe vertical heterojunction film as a pressure-sensitive layer, which is combined with the sensor substrate and the cavity on the second electrical insulating layer to serve as an absolute pressure cavity. A top electrode is provided on the top of the In2Se3 / InSe vertical heterojunction film to collect charges generated on the surface; a bottom electrode is provided on the bottom to collect charges generated on the bottom surface and form a conductive loop with the top electrode; side electrodes are provided on the side to collect charges escaping from the side to enhance the piezoelectric effect; and there is sufficient insulation isolation between the electrodes to avoid short circuits. A first electrical insulating layer is also provided at the bottom of the substrate to isolate electrical signals, isolate the outside air, form an internal and external pressure difference, and serve as a support for the bottom of the sensor.

[0068] The working principle of the piezoelectric air pressure sensor designed by the present invention is as follows (the working principle diagram is as follows Figure 3 shown):

[0069] In the In2Se3 / InSe vertical heterojunction, both In2Se3 and InSe have hexagonal unit cells with a lattice mismatch ratio of 0.2%. (The spatial distribution diagram of the In2Se3 / InSe heterojunction is shown in Figure 2.) Figure 4As shown, the green balls represent Se atoms and the purple balls represent In atoms. This primary structure lacks centrosymmetry at any thickness and exhibits out-of-plane (d33) piezoelectricity. Therefore, in the pressure sensor of the present invention, the In2Se3 / InSe vertical heterojunction exhibits a piezoelectric effect, and its upper and lower electrodes generate a piezoelectric voltage when subjected to external pressure. Specifically, when the external air pressure changes, a pressure differential is generated inside and outside the cavity formed by the In2Se3 / InSe heterojunction film, the sensor substrate, and the cavity on the electrically insulating layer 2. The In2Se3 / InSe heterojunction film deforms downward, and the stress in the d33 direction changes. The In2Se3 / InSe heterojunction band gap decreases, generating an internal electric dipole related to the displacement of the indium cation and the selenide anion. The electric field triggered by the electric dipole is further superimposed along the polarization direction (d33), generating an out-of-plane piezoelectric field on a macroscopic scale, which manifests as a piezoelectric voltage. The magnitude of the piezoelectric voltage is linearly related to the air pressure. When the pressure differential increases, the downward bowing of the In2Se3 / InSe heterojunction film increases, increasing the internal stress of the film, increasing the band gap change, and thus increasing the piezoelectric voltage. When the pressure differential decreases, the downward bowing of the In2Se3 / InSe heterojunction film decreases, reducing the internal stress and generating a reverse piezoelectric voltage. Therefore, a relationship can be established between the pressure differential inside and outside the cavity and the piezoelectric voltage, and the real-time air pressure can be determined by detecting the voltage change.

[0070] The out-of-plane piezoelectric properties of the In2Se3 / InSe vertical heterojunction are highly sensitive to strain, varying by more than two orders of magnitude, while maintaining excellent compatibility with silicon semiconductor technology. The pressure sensor of this invention utilizes an innovative piezoelectric pressure detection principle, theoretically guaranteeing high pressure detection accuracy and demonstrating the potential for detecting very low pressures.

[0071] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0072] Example 1

[0073] A piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction comprises a first electrical insulating layer, a substrate, a second electrical insulating layer, a bottom electrode, a pressure sensitive layer, a top electrode, and side electrodes;

[0074] The first electrical insulating layer and the second electrical insulating layer are respectively arranged on both sides of the substrate, and the bottom electrode is embedded in the upper surface of the second electrical insulating layer; the air pressure sensitive layer is arranged on the upper surface of the bottom electrode and the second electrical insulating layer, and the top electrode is arranged on the upper surface of the air pressure sensitive layer; the side electrode is arranged on the side of the air pressure sensitive layer;

[0075] The substrate and the second electrical insulating layer are provided with 16 penetrating micro-nanoscale arrayed cavities. The cavities are circular in shape and arranged in parallel. The pore radius is 8 μm and the pore spacing is 10 μm.

[0076] The pressure sensitive layer is an In2Se3 / InSe vertical heterojunction film, including an In2Se3 layer (1.5nm thick) and an InSe layer (2nm thick). The InSe layer is arranged on the upper surface of the bottom electrode and the second electrical insulating layer (InSe contacts the bottom electrode), and the In2Se3 layer is partially overlapped on the upper surface of the InSe layer (In2Se3 contacts the top electrode). The In2Se3 / InSe vertical heterojunction film can be divided into three parts in the horizontal direction: a part with only InSe, a part with only In2Se3, and a part where In2Se3 and InSe overlap to form a vertical The vertical heterojunction portion; the portion where In2Se3 and InSe overlap to form a vertical heterojunction completely covers the micro-nanoscale arrayed cavities on the substrate and the second electrical insulating layer, forming a cavity isolated from the external atmospheric pressure (a closed absolute pressure cavity); the top electrode is located on the portion where only In2Se3 is present, and the bottom electrode is located on the portion where only InSe is present; the side electrodes are located on the side of the In2Se3 portion, covering the outer edge of the In2Se3 portion, and are π-shaped. The side electrodes fully cover the vertical direction and extend horizontally to 40% of the horizontal length of the In2Se3 / InSe vertical heterojunction film;

[0077] The first electrical insulating layer is made of silicon nitride with a thickness of 200nm; the substrate is a silicon wafer with a thickness of 500μm; the second electrical insulating layer is made of silicon dioxide with a thickness of 300nm;

[0078] The top electrode is made of Au with a thickness of 40 nm;

[0079] The bottom electrode is made of Au with a thickness of 40nm;

[0080] The side electrodes are made of Au with a thickness of 20 nm.

[0081] The steps for preparing the sensor are as follows:

[0082] A first electrical insulating layer is formed on the lower surface of the substrate, and a second electrical insulating layer is formed on the upper surface of the substrate;

[0083] Spin-coating photoresist on the surface of the second electrical insulating layer and patterning it by photolithography, and then forming micro-nanoscale arrayed cavities penetrating the second electrical insulating layer and the substrate by dry etching;

[0084] forming a bottom electrode on the second electrical insulating layer by photolithography and magnetron sputtering;

[0085] By layer-by-layer transfer, an In2Se3 / InSe vertical heterojunction film is prepared on the surface of the second electrical insulating layer after the micro-nanoscale arrayed cavities are formed and the bottom electrode is prepared;

[0086] A top electrode was prepared on the surface of the In2Se3 / InSe vertical heterojunction film, and a side electrode was prepared on the side by photolithography and magnetron sputtering, thereby obtaining a piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction.

[0087] Comparative Example 1

[0088] The same as embodiment 1, the only difference is that the side electrodes are omitted.

[0089] Effect verification

[0090] The piezoelectric pressure sensors prepared in Example 1 and Comparative Example 1 were tested. The test system included a piezoelectric pressure sensor, a charge amplifier, a data acquisition card (VDS1022), a host computer software, and a standard pressure test bench (PACE6000). Air pressure was applied at different points within the range of 100Pa-1000Pa, and the host computer data results were recorded. The real-time pressure changes at 200Pa, 500Pa, and 800Pa are shown in Figure 2. Figure 5 As shown ( Figure 5 Only the test results of Example 1 are shown). Multiple sets of data are recorded to obtain the relationship between air pressure and voltage, such as Figure 6 As shown ( Figure 6 The test results of Example 1 (with side electrodes) and Comparative Example 1 (without side electrodes) are shown. Figure 5 and Figure 6 It can be seen that the magnitude of the piezoelectric voltage is linearly related to the gas pressure. When the internal and external pressure differential increases, the downward bending of the In2Se3 / InSe heterojunction film increases, increasing the internal stress of the film, increasing the band gap change, and increasing the piezoelectric voltage. Simultaneously, when the internal and external pressure differential decreases, the downward bending of the In2Se3 / InSe heterojunction film decreases, reducing the internal stress of the film and generating a reverse piezoelectric voltage. Compared with sensors without side electrodes, devices with side electrodes exhibit a larger voltage change under the same gas pressure change, facilitating subsequent output signal detection and further sensitivity modulation.

[0091] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction, characterized in that: The device comprises a first electrically insulating layer, a substrate, a second electrically insulating layer, a bottom electrode, an air pressure sensitive layer, a top electrode, and side electrodes located on the sides of the air pressure sensitive layer; wherein the first electrically insulating layer and the second electrically insulating layer are respectively arranged on both sides of the substrate, the bottom electrode is embedded on the upper surface of the second electrically insulating layer; the air pressure sensitive layer is arranged on the upper surfaces of the bottom electrode and the second electrically insulating layer, and the top electrode is arranged on the upper surface of the air pressure sensitive layer; The pressure sensitive layer is an In2Se3 / InSe vertical heterojunction film; The substrate and the second electrical insulating layer are provided with penetrating micro-nanoscale arrayed cavities.

2. The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction according to claim 1, characterized in that: The In2Se3 / InSe vertical heterojunction film includes an In2Se3 layer and an InSe layer, the InSe layer is arranged on the upper surface of the bottom electrode and the second electrical insulating layer, and the In2Se3 layer is partially overlapped on the upper surface of the InSe layer or completely covers the upper surface of the InSe layer; the thickness of the In2Se3 layer is 1-10nm, and the thickness of the InSe layer is 0.7-10nm.

3. The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction according to claim 1, characterized in that: The side electrode covers the outer edge of the air pressure sensitive layer.

4. The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction according to claim 1, characterized in that: The substrate is a silicon wafer; the second electrical insulating layer is made of silicon dioxide with a thickness of 200-1000 nm.

5. The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction according to claim 1, characterized in that: The hole shape of the micro-nanoscale arrayed cavities is circular, square or rectangular; the arrangement of the micro-nanoscale arrayed cavities is parallel arrangement or hexagonal arrangement; the hole center spacing of the micro-nanoscale arrayed cavities is 6-20 μm.

6. The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction according to claim 1, characterized in that: The top electrode is made of gold, platinum, nickel, silver paste or conductive polymer; the bottom electrode is made of gold, platinum, nickel, silver paste or conductive polymer; the side electrode is made of gold, platinum, nickel, silver paste or conductive polymer.

7. A method for preparing a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction according to any one of claims 1 to 6, characterized in that: The following steps are involved: A first electrical insulating layer is formed on the lower surface of the substrate, and a second electrical insulating layer is formed on the upper surface of the substrate; Spin-coating photoresist on the surface of the second electrical insulating layer, patterning it by photolithography, and then forming micro-nanoscale arrayed cavities penetrating the second electrical insulating layer and the substrate by dry etching; forming a bottom electrode on the second electrical insulating layer by photolithography and magnetron sputtering; By layer-by-layer transfer, an In2Se3 / InSe vertical heterojunction film is prepared on the surface of the second electrical insulating layer after the micro-nanoscale arrayed cavities are formed and the bottom electrode is prepared; A top electrode is prepared on the surface of the In2Se3 / InSe vertical heterojunction film, and a side electrode is prepared on the side by photolithography and magnetron sputtering, thereby obtaining the piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction.

8. Application of a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction according to any one of claims 1 to 6 in high-precision pressure detection.

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