阅读说明：本技术 一种异质结红外光电传感器及其制备方法 (Heterojunction infrared photoelectric sensor and preparation method thereof ) 是由 张洪宾 陆佳俊 佀国翔 吕绍艳 程瑞杉 徐彦彩 李娇 孙硕齐 于 2021-07-09 设计创作，主要内容包括：本公开提供了一种异质结红外光电传感器及其制备方法,采用基于Cu/SnSe/Ge/In-Ga的异质结的光电传感器；将SnSe/Ge的异质结作为光吸收活性层,在SnSe/Ge的异质结的界面处形成电场；将Cu的微栅格结构作为顶电极,与SnSe的晶体薄膜形成欧姆接触；将In-Ga合金或In的晶体薄膜作为底电极,与Ge的晶体基片形成欧姆接触。在红外光的照射下实现红外光学信号到电学信号的转换,实现对红外光的快速识别,同时,能够感知微弱的光信号,解决目前红外传感器件普遍存在的较小光电流和较大暗电流的难题,进而提高了红外传感器识别的灵敏度和探测度。(The present disclosure provides a heterojunction infrared photoelectric sensor and a preparation method thereof, wherein the photoelectric sensor is a heterojunction based on Cu/SnSe/Ge/In-Ga; forming an electric field at an interface of the SnSe/Ge heterojunction, wherein the SnSe/Ge heterojunction is used as a light absorption active layer; taking the micro-grid structure of Cu as a top electrode to form ohmic contact with the SnSe crystal film; and forming ohmic contact with the Ge crystal substrate by using the In-Ga alloy or the In crystal film as a bottom electrode. The infrared sensor has the advantages that conversion from an infrared optical signal to an electrical signal is realized under the irradiation of infrared light, the infrared light is rapidly identified, meanwhile, a weak optical signal can be sensed, the problems of small photocurrent and large dark current commonly existing in the existing infrared sensor are solved, and the identification sensitivity and detection degree of the infrared sensor are further improved.)

1. A heterojunction infrared photoelectric sensor is characterized In that the photoelectric sensor based on a Cu/SnSe/Ge/In-Ga heterojunction is adopted; forming an electric field at an interface of the SnSe/Ge heterojunction, wherein the SnSe/Ge heterojunction is used as a light absorption active layer; taking the micro-grid structure of Cu as a top electrode to form ohmic contact with the SnSe crystal film; and forming ohmic contact with the Ge crystal substrate by using the In-Ga alloy or the In crystal film as a bottom electrode.

2. A heterojunction infrared photosensor according to claim 1 wherein said crystalline thin film of SnSe is set to 50-90nm in thickness and 2.20 x 10 in resistivity³Omega cm, the conductivity type is set to be P type.

3. A heterojunction infrared photoelectric sensor as claimed in claim 1, wherein said Ge crystal substrate is set to a thickness of 100-200 μm, resistivity is set to 1.0-5.0 Ω -cm, and conductivity type is N-type.

4. A heterojunction infrared photosensor according to claim 1, wherein said top electrode is set to 60-100nm in thickness, is set to a fishbone-like structure, is set to 100 μm in line width, is set to 4.8mm in line length, and is set to 500 μm in interval.

5. A heterojunction infrared photosensor according to claim 1, wherein said bottom electrode is provided with a thickness of 60 to 100 nm.

6. A heterojunction infrared photosensor according to claim 1 wherein said heterojunction photosensors of Cu/SnSe/Ge/In-Ga are arranged as square devices with dimensions of 5mm x 200 μm.

7. A heterojunction infrared photosensor according to claim 1 wherein the infrared wavelengths sensed by the photosensors of Cu/SnSe/Ge/In-Ga heterojunction are 1064nm, 1310nm and 1550 nm.

8. A preparation method of a heterojunction infrared photoelectric sensor is characterized by comprising the following steps:

obtaining a Ge substrate with a clean surface based on the Ge crystal substrate, and constructing a high-crystallinity SnSe crystal thin film on the Ge substrate to obtain a SnSe/Ge heterojunction with an electrical abrupt junction;

preparing a Cu grid electrode on one side of the SnSe crystal film on the heterojunction of the SnSe/Ge to obtain the heterojunction of the Cu/SnSe/Ge;

and preparing an In-Ga alloy or an In electrode at one side of the Ge crystal substrate on the Cu/SnSe/Ge heterojunction to obtain the infrared photoelectric sensor with the Cu/SnSe/Ge/In-Ga heterojunction.

9. The method for manufacturing a heterojunction infrared photoelectric sensor as claimed in claim 8, wherein the Ge crystal substrate is processed by an ultrasonic cleaning device to obtain a Ge substrate with a clean surface, and the physical vapor deposition method or the magnetron sputtering combined with the post-annealing process is adopted to construct the SnSe crystal thin film with high crystallinity on the Ge substrate.

10. The method of claim 8, wherein a Cu grid electrode having a structure determined by a mask or a photolithography process is formed on the side of the SnSe crystal thin film on the heterojunction of the SnSe/Ge by a vacuum thermal evaporation, magnetron sputtering or electron beam evaporation process, and an In-Ga alloy layer is spin-coated or an In thin film layer is evaporated on the side of the Ge crystal substrate by a spin coating process as a bottom contact ohmic electrode of the device.

Technical Field

The disclosure belongs to the technical field of photoelectric materials and devices, and particularly relates to a heterojunction infrared photoelectric sensor and a preparation method thereof.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

The sensors are the bottommost layer and the frontmost edge of the technology of the Internet of things, are the first links for realizing automatic detection and automatic control, and have very important significance for the development of the industry of the Internet of things. Therefore, with the wave of emerging sensing technologies such as intelligent identification and mobile interconnection, the infrared sensor industry also meets a huge development opportunity, and the market demand scale is rapidly expanded. However, the infrared sensors on the market generally have the disadvantages of low sensitivity, long response time, large volume, requirement of external power supply and the like, and are difficult to meet the technical requirements of a series of emerging fields such as portability, low energy consumption, mobile interconnection and the like. In this context, it is particularly important to design and develop a heterojunction photoelectric sensor based on infrared photon energy.

Due to a plurality of new characteristics of the two-dimensional semiconductor Van der Waals heterojunction, the two-dimensional semiconductor Van der Waals heterojunction has wide application prospects in the fields of electronic and optoelectronic devices, and attracts people's attention. Two-dimensional van der waals heterojunctions can exhibit properties that exceed those of two materials, and are combined together by weak van der waals forces, thus providing more flexibility in the choice of material type and lattice structure, and avoiding severe recombination effects of interfacial dangling bonds on photogenerated carriers. The two-dimensional van der Waals heterojunction can form a steady built-in potential barrier at the interface, so that photoexcited carriers can be effectively separated, and the internal transit time of the two-dimensional van der Waals heterojunction is shortened, so that the output of external photocurrent of the heterojunction is greatly improved, the two-dimensional van der Waals heterojunction has an important application value in the aspect of constructing high-performance optoelectronic devices, and becomes a new hotspot for research of self-driven and high-sensitivity infrared photoelectric sensors.

The inventors have appreciated that the fabrication of high performance infrared photosensors relies closely on active layer materials having a high carrier mobility and a large light absorption coefficient. Binary SnSe is a group IV-VI P-type semiconductor, generally presents a layered orthorhombic structure, is considered to be a two-dimensional photoelectric functional material with excellent performance, and has the hole concentration of 10¹⁶～10¹⁸cm^-3The material has a large light absorption coefficient in a near infrared band, and is a potential material for preparing an infrared photoelectric sensor. In addition, the single crystal germanium serving as an indirect bandgap semiconductor material not only has a wider light absorption spectrum range, but also has higher carrier mobility, and is an ideal material for preparing various photoelectronic devices. The currently reported light guide type infrared photoelectric sensing device based on a single material generally has larger dark current and smaller photocurrent, so that the detectivity and responsivity of the device are not high, and the sensing application of weak light and infrared light with smaller photon energy is seriously limited; however, due to the transfer behavior of majority carriers on the interface of the P-type SnSe and the N-type Ge, a P-N junction with excellent performance can be formed, and the separation capability of photogenerated carriers of the device under the irradiation of infrared light can be improved.

Therefore, how to prepare a high-performance infrared sensing photoelectric sensor based on a two-dimensional SnSe/Ge heterojunction to solve the ubiquitous problem of the existing infrared sensor has important practical significance for the development of the infrared sensing industry.

Disclosure of Invention

In order to solve the problems, the present disclosure provides a heterojunction infrared photoelectric sensor and a manufacturing method thereof, which realize conversion from an infrared optical signal to an electrical signal under irradiation of infrared light, realize rapid identification of the infrared light, and simultaneously sense a weak optical signal, thereby solving the problems of a small photocurrent and a large dark current commonly existing in the existing infrared sensing device, and further improving the sensitivity and the detectivity of the infrared sensor identification.

According to some embodiments, a first aspect of the present disclosure provides a heterojunction infrared photoelectric sensor, which adopts the following technical solutions:

a heterojunction infrared photoelectric sensor adopts a photoelectric sensor based on a Cu/SnSe/Ge/In-Ga heterojunction; forming an electric field at an interface of the SnSe/Ge heterojunction, wherein the SnSe/Ge heterojunction is used as a light absorption active layer; taking the micro-grid structure of Cu as a top electrode to form ohmic contact with the SnSe crystal film; and forming ohmic contact with the Ge crystal substrate by using the In-Ga alloy or the In crystal film as a bottom electrode.

According to some embodiments, a second aspect of the present disclosure provides a method of fabricating a heterojunction infrared photosensor.

A preparation method of a heterojunction infrared photoelectric sensor comprises the following steps:

obtaining a Ge substrate with a clean surface based on the Ge crystal substrate, and constructing a high-crystallinity SnSe crystal thin film on the Ge substrate to obtain a SnSe/Ge heterojunction with an electrical abrupt junction;

preparing a Cu grid electrode on one side of the SnSe crystal film on the heterojunction of the SnSe/Ge to obtain the heterojunction of the Cu/SnSe/Ge;

and preparing an In-Ga alloy or an In electrode at one side of the Ge crystal substrate on the Cu/SnSe/Ge heterojunction to obtain the infrared photoelectric sensor with the Cu/SnSe/Ge/In-Ga heterojunction.

Compared with the prior art, the beneficial effect of this disclosure is:

(1) the infrared photoelectric sensor fully utilizes the high infrared absorption characteristics of the SnSe crystal film and the Ge wafer; when infrared light is irradiated to the top of the device, the SnSe crystal thin film and the Ge wafer simultaneously absorb incident light, resulting in a large number of excited electron transitions from the valence band to the conduction band, thereby generating a sufficient number of electron-hole pairs in the device.

(2) The conduction band energy level (Ec) and the valence band energy level (Ev) of the N-type Ge wafer are 4.13eV and 4.79eV respectively, and the conduction band energy level (Ec) and the valence band energy level (Ev) of the P-type SnSe crystal film are 4.18eV and 5.08eV respectively; when the P-type SnSe crystal film is deposited on the N-type Ge wafer, a stable P-N heterojunction can be formed at the interface of the P-type SnSe crystal film due to different energy levels of materials, and a larger built-in electric field enables photoexcited electron-hole pairs to directionally flow, wherein photoexcited electrons are driven into the N-type Ge wafer, and photoexcited holes are driven into the P-type SnSe crystal film, so that the rapid recombination effect of excited carriers is remarkably reduced, and the sensitivity and the detection degree of a device are improved.

(3) In the preparation method of the infrared sensor, the Cu microstructure is used as a top contact electrode of a device, so that effective light transmission of infrared light is ensured, and separation and transmission efficiency of photoproduction cavities is remarkably improved; the In-Ga alloy or the In film is used as a bottom electrode of the device, so that good ohmic contact can be formed with the N-type Ge wafer, and the collection and transmission of photo-generated electrons are facilitated. Combining the effects of the preferred electrodes, the infrared sensor of the present disclosure has a maximum photocurrent (71.25mA) output, ultra-large responsivity (45A/W) and detection level (1.4X 10)¹²Jones), and an ultra-fast response speed (5.47 mus), and the like, and can meet the technical requirements of the market on high sensitivity, high response speed and the like of the infrared sensor.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.

Fig. 1 is a schematic structural diagram of a heterojunction infrared photosensor in accordance with an embodiment of the present disclosure;

FIG. 2 is a surface and Scanning Electron Microscope (SEM) effect of the SnSe/Ge heterojunction in one embodiment of the disclosure;

fig. 3 is a graph of photocurrent output and photoresponse of a photoelectric sensor of a Cu/SnSe/Ge/In-Ga heterojunction under 1064nm infrared light irradiation In an embodiment of the disclosure.

The specific implementation mode is as follows:

the present disclosure is further described with reference to the following drawings and examples.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.

Example one

The present embodiment describes a heterojunction infrared photosensor.

The heterojunction infrared photoelectric sensor shown In the figures 1 and 2 adopts a photoelectric sensor based on a Cu/SnSe/Ge/In-Ga heterojunction; the heterojunction of SnSe/Ge is used as a light absorption active layer, the crystal thin film of SnSe and Ge has higher absorption degree to infrared light, and an electric field is formed at the interface of the heterojunction of SnSe/Ge, which is beneficial to the rapid separation of photon-generated carriers in the device, thereby obviously improving the formation of photocurrent, reducing the intensity of reverse saturation current and improving the capability of the device for detecting weak light; the micro-grid structure of Cu is used as a top electrode and forms ohmic contact with the SnSe crystal film, so that collection and transmission of photoproduction holes are facilitated; the In-Ga alloy or the In crystal film is used as a bottom electrode to form ohmic contact with the Ge crystal substrate, so that collection and transportation of photo-generated electrons are facilitated.

In the present embodiment, the photosensor of the heterojunction of Cu/SnSe/Ge/In-Ga is configured as a square device with length, width and height dimensions of about 5mm × 5mm × 200 μm; the heterojunction infrared photoelectric sensor is welded with a corresponding external lead, or welded in a related weak current system, or integrated in various chips, so that the sensing and detection application of infrared light can be realized.

The thickness of the SnSe crystal film is 50-90nm, and the resistivity is 2.20 × 10³Omega cm, the conductivity type is set as P type; the thickness of the Ge crystal substrate is set to be 100-200 mu m, the resistivity is set to be 1.0-5.0 omega-cm, and the conductivity type is set to be N type; the thickness of the top electrode is set to be 60-100nm, the structure is set to be a fishbone structure, the line width is set to be 100 mu m, the line length is set to be 4.8mm, and the interval is set to be 500 mu m; the thickness of the bottom electrode is set to 60-100 nm.

The infrared wavelengths sensed by the photoelectric sensor with the Cu/SnSe/Ge/In-Ga heterojunction are 1064nm, 1310nm and 1550nm, and fig. 3 is a photocurrent output curve graph and a photoresponse curve graph of the photoelectric sensor with the Cu/SnSe/Ge/In-Ga heterojunction under 1064nm infrared irradiation.

The heterojunction infrared photoelectric sensor in the embodiment fully utilizes the high infrared absorption characteristics of the SnSe crystal film and the Ge wafer; when infrared light is irradiated to the top of the device, the SnSe crystal thin film and the Ge wafer simultaneously absorb incident light, resulting in a large number of excited electron transitions from the valence band to the conduction band, thereby generating a sufficient number of electron-hole pairs in the device. The conduction band energy level (Ec) and the valence band energy level (Ev) of the N-type Ge wafer are 4.13eV and 4.79eV respectively, and the conduction band energy level (Ec) and the valence band energy level (Ev) of the P-type SnSe crystal film are 4.18eV and 5.08eV respectively; when the P-type SnSe crystal film is deposited on the N-type Ge wafer, a stable P-N heterojunction can be formed at the interface of the P-type SnSe crystal film due to different energy levels of materials, and a larger built-in electric field enables photoexcited electron-hole pairs to directionally flow, wherein photoexcited electrons are driven into the N-type Ge wafer, and photoexcited holes are driven into the P-type SnSe crystal film, so that the rapid recombination effect of excited carriers is remarkably reduced, and the sensitivity and the detection degree of a device are improved.

Example two

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

Using an N-type single crystal Ge substrate with resistivity of 1.0-5.0 omega-cm and thickness of 100-₂) And drying the substrate by blowing so as to obtain the Ge substrate with a clean surface. Subsequently, a layer having a thickness of about 70nm and a resistivity of about 2.20X 10 was grown on the Ge crystal substrate by a Physical Vapor Deposition (PVD) method using a high-purity (99.999%) SnSe powder as a growth source³The P-type layered SnSe crystal film of omega cm is used for preparing a SnSe/Ge heterojunction with the electrical rectification ratio as high as 200; in the growth process, the evaporation growth temperature is 600 ℃, the working pressure is 25Pa, the working gas is argon (Ar), the flow rate is 40sccm, and the growth time is controlled to be about 10 minutes.

A Cu grid electrode with the thickness of about 60nm is evaporated on the upper surface of the SnSe crystal film by using a vacuum evaporation method and is used as a top contact ohmic electrode of the infrared sensing device; taking Cu particles with high purity (99.999%) as an evaporation source, wherein the evaporation temperature is 1100 ℃, and the evaporation time is about 20 min; the specific structure and parameters of the Cu electrode are realized by the assistance of a pre-processed patterned metal mask. And then, preparing an In-Ga alloy layer with the thickness of about 100nm on the lower surface of the Ge substrate by a spin coating process to serve as a bottom contact ohmic electrode of the device, thereby constructing the heterojunction infrared photoelectric sensor.

EXAMPLE III

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

Using an N-type single crystal Ge substrate with resistivity of 1.0-5.0 omega-cm and thickness of 100-₂) And blow-drying the substrate to obtain the single crystal Ge substrate with a clean surface. Sputtering a layer of 70 nm-thick layered SnSe crystal film on a Ge substrate by adopting a magnetron sputtering method and taking a high-purity (99.999%) SnSe target as a sputtering source; wherein the diameter of the target is 50.8mm, the sputtering power is 50W, the working pressure is 10Pa, the working gas is argon (Ar), the flow rate is 50sccm, and the sputtering time is controlled to be about 20 minutes. Then, a rapid annealing furnace was used to treat the gas in a high purity nitrogen (N) atmosphere₂) Annealing the sputtered SnSe/Ge heterojunction for about 2.0 hours at 300 ℃ in an atmosphere to obtain an electric fieldThe conductivity type is P type, and the resistivity is about 2.20 multiplied by 10³The high crystallinity SnSe crystal film of omega cm, and further the SnSe/Ge heterojunction with high rectification ratio is obtained.

A Cu grid electrode with the thickness of about 60nm is evaporated on the upper surface of the SnSe crystal film by using a vacuum evaporation method and is used as a top contact ohmic electrode of the infrared sensing device; taking Cu particles with high purity (99.999%) as an evaporation source, wherein the evaporation temperature is 1100 ℃, and the evaporation time is about 20 min; the specific structure and parameters of the Cu electrode are realized by the assistance of a pre-processed patterned metal mask. Secondly, preparing an In film with the thickness of 60-100nm on the lower surface of the Ge crystal substrate as a bottom contact electrode of the device by adopting a vacuum thermal evaporation process, wherein the evaporation temperature is 160 ℃, the working gas is nitrogen, and the vacuum degree is about 10^-3Pa, the evaporation time is about 30min, the area of the In electrode is kept slightly smaller than the cross-sectional area of the heterojunction In order to ensure that the heterojunction is not short-circuited In the evaporation process, and finally the heterojunction infrared photoelectric sensor is constructed.

Example four

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

Using an N-type single crystal Ge substrate with resistivity of 1.0-5.0 omega-cm and thickness of 100-₂) And drying the substrate by blowing so as to obtain the Ge substrate with a clean surface. Subsequently, a layer having a thickness of about 70nm and a resistivity of about 2.20X 10 was grown on the Ge crystal substrate by a Physical Vapor Deposition (PVD) method using a high-purity (99.999%) SnSe powder as a growth source³The P-type layered SnSe crystal film of omega cm is used for preparing a SnSe/Ge heterojunction with the electrical rectification ratio as high as 200; in the growth process, the evaporation growth temperature is 600 ℃, the working pressure is 25Pa, the working gas is argon (Ar), the flow rate is 40sccm, and the growth time is controlled to be about 10 minutes.

Patterning the grown SnSe/Ge heterojunction by utilizing a photoetching process and fully with the assistance of a photoetching plate and photoresist, wherein the structure and the size of a photoresist window define the specific structure and the size of a Cu grid electrode; by utilizing a vacuum evaporation method, taking high-purity (99.999%) Cu particles as an evaporation source, and evaporating a Cu thin film with the thickness of about 60nm on a patterned SnSe/Ge heterojunction, wherein the evaporation temperature is 1100 ℃, and the evaporation time is about 20 min; subsequently, a top contact ohmic electrode of a Cu fishbone structure was obtained by a lift-off process. And secondly, preparing an In-Ga alloy layer with the thickness of about 100nm on the lower surface of the bottom Ge substrate of the prepared Cu/SnSe/Ge heterojunction by a spin coating process to serve as a bottom contact ohmic electrode of the device, thereby constructing the heterojunction infrared photoelectric sensor.

EXAMPLE five

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

Using an N-type single crystal Ge substrate with resistivity of 1.0-5.0 omega-cm and thickness of 100-₂) And blow-drying the substrate to obtain the single crystal Ge substrate with a clean surface. Sputtering a layer of 70 nm-thick layered SnSe crystal film on a Ge substrate by adopting a magnetron sputtering method and taking a high-purity (99.999%) SnSe target as a sputtering source; wherein the diameter of the target is 50.8mm, the sputtering power is 50W, the working pressure is 10Pa, the working gas is argon (Ar), the flow rate is 50sccm, and the sputtering time is controlled to be about 20 minutes. Then, a rapid annealing furnace was used to treat the gas in a high purity nitrogen (N) atmosphere₂) Annealing the sputtered SnSe/Ge heterojunction for about 2.0 hours under an atmosphere to obtain a P-type conductivity with a resistivity of about 2.20X 10³The high crystallinity SnSe crystal film of omega cm, and then the SnSe/Ge heterojunction with high rectification ratio is obtained.

By a magnetron sputtering process, a Cu target with the purity of 99.999 percent is used as a sputtering source, a Cu grid electrode with the thickness of about 60nm is sputtered on the upper surface of a growing SnSe/Ge heterojunction under the assistance of a pre-processed metal mask, and the Cu grid electrode is used as a top contact ohmic electrode of an infrared sensing device, wherein the diameter of the Cu target is 50.8mm, the sputtering power is 100W, the working gas is argon (Ar), the working pressure is 5.0Pa, the flow is 35sccm, and the sputtering time is about 25 minutes. And secondly, preparing an In-Ga alloy layer with the thickness of about 100nm on the lower surface of the bottom Ge substrate of the Cu/SnSe/Ge heterojunction by a spin coating process to serve as a bottom contact ohmic electrode of the device, so that the heterojunction infrared photoelectric sensor is constructed.

EXAMPLE six

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

Using an N-type single crystal Ge substrate with resistivity of 1.0-5.0 omega-cm and thickness of 100-₂) And drying the substrate by blowing so as to obtain the Ge substrate with a clean surface. Subsequently, a layer having a thickness of about 70nm and a resistivity of about 2.20X 10 was grown on the Ge crystal substrate by a Chemical Vapor Deposition (CVD) method using high purity (99.999%) Sn powder and Se powder as growth sources³The P-type layered SnSe crystal film of omega cm is used for preparing a SnSe/Ge heterojunction with the electrical rectification ratio as high as 200; in the process of film growth, the evaporation temperature of Sn powder and Se powder is 250 ℃, the working pressure is 30Pa, the working gas is argon (Ar), the flow rate is 30sccm, and the growth time is controlled to be about 30 minutes.

A Cu grid electrode with the thickness of about 60nm is evaporated on the upper surface of the SnSe thin film of the SnSe/Ge heterojunction by using a vacuum evaporation method and is used as a top contact ohmic electrode of the infrared sensing device; taking Cu particles with high purity (99.999%) as an evaporation source, wherein the evaporation temperature is 1100 ℃, and the evaporation time is about 20 min; the specific structure and parameters of the Cu electrode are realized by the assistance of a pre-processed patterned metal mask. And secondly, preparing an In-Ga alloy layer with the thickness of about 100nm on the lower surface of the Ge substrate of the SnSe/Ge heterojunction by a spin coating process to serve as a bottom contact ohmic electrode of the device, thereby constructing the heterojunction infrared photoelectric sensor.

EXAMPLE seven

The embodiment describes a preparation method of a heterojunction infrared photoelectric sensor.

With a resistivity of 1.0-5.0 omegaCm and a thickness of 100-₂) And blow-drying the substrate to obtain the single crystal Ge substrate with a clean surface. Sputtering a layer of 70 nm-thick layered SnSe film on a Ge substrate by adopting a magnetron sputtering method and taking a high-purity (99.999%) SnSe target as a sputtering source; wherein the diameter of the target is 50.8mm, the sputtering power is 50W, the working pressure is 10Pa, the working gas is argon (Ar), the flow rate is 50sccm, and the sputtering time is controlled to be about 20 minutes. Then, a rapid annealing furnace was used to treat the gas in a high purity nitrogen (N) atmosphere₂) Annealing the sputtered SnSe/Ge heterojunction for about 2.0 hours at 300 deg.C under an atmosphere to obtain a P-type conductivity with a resistivity of about 2.20 × 10³The high crystallinity SnSe crystal film of omega cm, and further the SnSe/Ge heterojunction with high rectification ratio is obtained.

Through an electron beam evaporation deposition process, a Cu grid electrode with the thickness of about 60nm is grown on the upper surface of the SnSe film of the annealed SnSe/Ge heterojunction in an evaporation mode and is used as a top contact ohmic electrode of the infrared sensing device; taking Cu particles with high purity (99.999%) as an evaporation source, wherein the evaporation rate is 2.0nm/min, and the evaporation time is about 30 min; the specific structure and parameters of the Cu electrode are realized by the assistance of a pre-processed patterned metal mask. And secondly, preparing an In-Ga alloy layer with the thickness of about 100nm on the lower surface of the bottom Ge substrate of the prepared Cu/SnSe/Ge heterojunction by a spin coating process to serve as a bottom contact ohmic electrode of the device, thereby constructing the heterojunction infrared photoelectric sensor.

Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.