Piezoelectric air pressure sensor based on In2Se3 / InSe vertical heterojunction and preparation method and application thereof

Abstract

The invention discloses a piezoelectric air pressure sensor based on an In2Se3 / InSe vertical heterojunction and a preparation method and application of the piezoelectric air pressure sensor, and belongs to the technical field of sensing instrument construction. The In2Se3 / InSe vertical heterojunction thin film is used as an air pressure sensitive layer to prepare the piezoelectric type air pressure sensor, stress change caused by air pressure changes the energy band structure of the In2Se3 / InSe vertical heterojunction, and therefore piezoelectric voltage is generated. The change can be monitored by detecting the voltage change through the charge amplifier, so that high-sensitivity response to tiny air pressure change is realized. The piezoelectric air pressure sensor is small in size and high in sensitivity, and simple, sensitive and stable equipment and a detection method are provided 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] Pressure sensors are mainly used in weather forecasting, altitude measurement, self-driving cars, drones, smart homes, industrial automation, the Internet of Things, aerospace, smart wearables and other fields. A typical pressure sensor generally contains a sensitive unit that generates strain with changes in pressure. The strain response of the sensitive unit brings about changes in the resistance or capacitance of the sensor. The rapid development of the Internet of Things, aerospace, smart wearables and other fields has put forward higher requirements for pressure sensors. It is necessary to continuously reduce the size of devices and packages while ensuring high precision and strong stability, and continue to miniaturize. The contradiction between miniaturization and high precision has given rise to the emergence and development of pressure sensors based on two-dimensional materials. This type of pressure sensor uses two-dimensional materials as a sensitive structure and is mainly based on electrical transconductance and piezoresistivity readings. Both rely on the change of membrane conductance with the deflection of the membrane, and then use this change to sense the movement of the membrane and then convert it into air pressure. However, pressure sensors based on these two detection principles have the problems of requiring external power supply to work, slow detection response speed, low sensitivity and low precision. Therefore, it is necessary to develop high-performance pressure sensors based on new detection principles. Summary of the invention

[0003] The purpose of the present invention is to provide a piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction and its preparation method and application, so as to solve the problems existing in the above-mentioned prior art. The present invention prepares a piezoelectric pressure sensor using In2Se3 / InSe vertical heterojunction film as the 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, and provides 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 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 on 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 air 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 concave cavities.

[0008] Further, the In2Se3 / InSe vertical heterojunction film includes an In2Se3 layer and an InSe layer, wherein the InSe layer is disposed on the upper surface of the bottom electrode and the second electrical insulating layer (InSe is in contact with the bottom electrode), 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 (In2Se3 is in contact with the top electrode); the thickness of the In2Se3 layer is 1-10nm, and the thickness of the InSe layer is 0.7-10nm. The vertical heterojunction formed by the In2Se3 layer and the InSe (with a lattice constant close to that of In2Se3) layer is specifically a two-dimensional vertical van der Waals heterojunction.

[0009] Furthermore, the piezoelectric air pressure sensor also 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 air 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 on 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, and the side electrode fully covers the vertical direction, and extends in the horizontal direction 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 is 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, and the side electrode completely covers the vertical direction, and extends in the horizontal direction 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 concave cavities on the substrate and the second electrical 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-nano-scale arrayed cavity is circular, square or rectangular; the arrangement of the micro-nano-scale arrayed cavity includes parallel arrangement or hexagonal arrangement; the hole center spacing of the micro-nano-scale arrayed cavity is 6-20 μm.

[0016] Furthermore, when the hole shape of the micro-nano-scale arrayed cavity is circular, the hole radius is 3-20 μm; when the hole shape of the micro-nano-scale 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 electrode is 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 preparation method of the above-mentioned piezoelectric pressure sensor based on 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] preparing 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] Technical solution three of the present invention: Application of the above-mentioned piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction in high-precision air pressure detection.

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

[0030] (1) The air pressure sensor of the present invention actually follows the piezoelectric air pressure detection principle based on the In2Se3 / InSe vertical heterojunction when in use, 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 air pressure detection. The present invention makes full use of the high-speed carrier mobility of In2Se3 and InSe to improve the response speed of the sensor. The air pressure sensor of the present invention responds sensitively to small changes in air pressure.

[0031] (2) Compared with the existing two-dimensional piezoelectric material system air pressure sensor, the present invention introduces the design of side electrodes, which can be connected to the top electrode as auxiliary electrodes to enhance the collection of charges escaping from the side of the In2Se3 material, forming a larger effective electrode area and increasing 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

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

[0034] Figure 2 A top view of a piezoelectric pressure sensor based on an 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 should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

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

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 a conflict with any incorporated document, the content 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 of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are 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 (Top view of the air pressure sensor), the present invention provides a piezoelectric air 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, an air 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 on the upper surface of the second electrical insulating layer; the air 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 air pressure sensitive layer;

[0045] The gas pressure sensitive layer is an In2Se3 / InSe vertical heterojunction film, including an In2Se3 layer and an InSe layer, wherein the InSe layer is arranged on the upper surface of the bottom electrode and the second electrical insulating layer (InSe is in contact with the bottom electrode), 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 (In2Se3 is in contact with the top electrode);

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

[0047] The piezoelectric air pressure sensor further comprises a side electrode located on the side of the air pressure sensitive layer, wherein the side electrode covers the 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 is 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, and the side electrode fully covers the vertical direction, and extends in the horizontal direction 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);

[0049] When the In2Se3 layer completely covers the upper surface of the InSe layer, the In2Se3 / InSe vertical heterojunction film is 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, and the side electrode completely covers the vertical direction, and extends in the horizontal direction 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 concave cavities on the substrate and the second electrical 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 type Π 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 200-1000nm.

[0053] As a preferred embodiment of the present invention, the hole 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 spacing of the holes in the micro-nanoscale arrayed cavities is 6-20μm.

[0054] As a preferred embodiment of the present invention, when the hole shape of the micro-nano arrayed cavity is circular, the hole radius is 3-20 μm; when the hole shape of the micro-nano 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; 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 of using 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 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] preparing 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 the application of the above-mentioned piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction in high-precision air pressure detection.

[0067] The piezoelectric pressure sensor based on the In2Se3 / InSe vertical heterojunction of the present invention adopts the In2Se3 / InSe vertical heterojunction film as the pressure sensitive layer, which is combined with the sensor substrate and the cavity on the second electrical insulating layer as an absolute pressure cavity. A top electrode is arranged on the top of the In2Se3 / InSe vertical heterojunction film to collect the charges generated on the surface; a bottom electrode is arranged on the bottom to collect the charges generated on the bottom surface and form a conductive loop with the top electrode; a side electrode is arranged on the side to collect the charges escaping from the side to enhance the piezoelectric effect; there is sufficient insulation isolation between the electrodes to avoid short circuits. A first electrical insulating layer is also arranged 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 bottom support for 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, and the lattice mismatch ratio is 0.2%. (The spatial distribution diagram of the In2Se3 / InSe heterojunction is shown in Figure 4As shown, the green balls represent Se atoms and the purple balls represent In atoms). This main structure always lacks central symmetry at any thickness and is out-of-plane (d33) piezoelectric. Therefore, in the pressure sensor of the present invention, the In2Se3 / InSe vertical heterojunction has a piezoelectric effect, and its upper and lower electrodes will generate a piezoelectric voltage when the external pressure acts. Specifically, when the external air pressure changes, a pressure difference will be generated inside and outside the cavity formed by the In2Se3 / InSe heterojunction film and the sensor substrate and the concave cavity on the electrical insulating layer 2, the In2Se3 / InSe heterojunction film will deform downward, the stress in the d33 direction will change, the In2Se3 / InSe heterojunction band gap will decrease, and an internal electric dipole related to the displacement of the cationic indium and the anionic selenide will be generated. The electric field triggered by the electric dipole will be further superimposed along the polarization direction (d33), and an out-of-plane piezoelectric field will be generated macroscopically, which is manifested as a piezoelectric voltage. The magnitude of the piezoelectric voltage is linearly related to the magnitude of the air pressure. When the pressure difference between the inside and outside increases, the degree of the downward bending of the In2Se3 / InSe heterojunction film increases, the stress in the film increases, the change in the band gap increases, and the piezoelectric voltage increases; when the pressure difference between the inside and outside decreases, the degree of the downward bending of the In2Se3 / InSe heterojunction film decreases, the stress in the film decreases, and a reverse piezoelectric voltage is generated. Therefore, the relationship between the pressure difference between the inside and outside of the cavity and the piezoelectric voltage can be established, and the real-time air pressure can be obtained by detecting the voltage change.

[0070] The out-of-plane piezoelectric performance of the In2Se3 / InSe vertical heterojunction is very sensitive to strain, with a change value of more than two orders of magnitude, and has good compatibility with silicon semiconductor technology. The air pressure sensor of the present invention is innovative in the air pressure detection principle (adopting the piezoelectric air pressure detection principle), theoretically guarantees the accuracy of air pressure detection, and has the potential for micro pressure detection.

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

[0072] Example 1

[0073] A piezoelectric air 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, an air pressure sensitive layer, a top electrode and a side electrode;

[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 on 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, arranged in parallel, with a pore radius of 8 μm and a pore spacing of 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 is in contact with the bottom electrode), and the In2Se3 layer is partially overlapped on the upper surface of the InSe layer (In2Se3 is in contact with 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 part of the vertical heterojunction formed by the overlap of In2Se3 and InSe completely covers the micro-nanoscale arrayed concave cavity 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 part with only In2Se3, and the bottom electrode is located on the part with only InSe; the side electrode is located on the side of the In2Se3 part, covering the outer edge of the In2Se3 part, and the shape is Π-type. The side electrode is fully covered in the vertical direction and extends in the horizontal direction to cover 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 40nm;

[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, patterning it by photolithography, and then forming micro-nanoscale arrayed concave 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 the first embodiment, the only difference is that the side electrode is 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 air pressure changes of 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, i.e., with side electrodes, and Comparative Example 1, i.e., 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 magnitude of the air pressure. When the internal and external pressure difference increases, the degree of downward bending of the In2Se3 / InSe heterojunction film increases, the stress in the film increases, the change in the band gap increases, and the piezoelectric voltage increases; at the same time, when the internal and external pressure difference decreases, the degree of downward bending of the In2Se3 / InSe heterojunction film decreases, the stress in the film decreases, and a reverse piezoelectric voltage is generated. Compared with sensors without side electrodes, devices with side electrodes have a larger voltage change amplitude under the same air pressure change, which is convenient for subsequent output signal detection and further sensitivity modulation.

[0091] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction, characterized in that: It comprises a first electrical insulating layer, a substrate, a second electrical insulating layer, a bottom electrode, an air 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 on the upper surface of the second electrical insulating layer; the air 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 air pressure sensitive layer; The air 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 concave cavities.

2. The piezoelectric pressure sensor based on 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, wherein 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 2, characterized in that: The piezoelectric air pressure sensor further includes a side electrode located on a side of the air pressure sensitive layer.

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

5. The piezoelectric pressure sensor based on 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 200-1000nm.

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

7. The piezoelectric pressure sensor based on 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.

8. A method for preparing a piezoelectric pressure sensor based on an In2Se3 / InSe vertical heterojunction as claimed in any one of claims 3 to 7, 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; preparing 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.

9. Application of a piezoelectric pressure sensor based on In2Se3 / InSe vertical heterojunction as described in any one of claims 1 to 7 in high-precision pressure detection.

Images