Photoelectric detector based on two-dimensional GaSe and InSb heterojunction and preparation method thereof

Abstract

The invention discloses a photoelectric detector based on a two-dimensional GaSe and InSb heterojunction and a preparation method of the photoelectric detector. The preparation method comprises the steps that S1, a metal bottom electrode is deposited at the bottom of a single-crystal InSb substrate in an ultrahigh vacuum thermal evaporation mode; s2, growing a two-dimensional GaSe thin film layer on the surface of the single crystal InSb substrate by adopting an ultrahigh vacuum molecular beam epitaxy mode; s3, depositing a transparent ITO (Indium Tin Oxide) top electrode on the surface of the grown two-dimensional GaSe thin film layer by adopting a direct-current magnetron sputtering mode; based on a synergistic effect between a photovoltaic effect brought by a built-in electric field between an n-type InSb heterojunction and a p-type GaSe heterojunction and a photo-thermal electric effect in GaSe, the device has remarkable photoresponse to light from near-infrared band to middle-infrared band, and has relatively good responsivity and detection rate; the two-dimensional material infrared photoelectric detector has the advantages of wide wave band, high response, self-driving and the like, the preparation process is high in stability and is combined with the current semiconductor industrial production mode, and a new thought is provided for the field of advanced two-dimensional material infrared photoelectric detectors.

Description

Technical Field

[0001] The invention belongs to the field of photoelectron detectors, and in particular relates to a photoelectric detector based on a two-dimensional GaSe and InSb heterojunction and a preparation method thereof. Background Art

[0002] A photodetector is an optoelectronic device that converts incident light signals into electrical signals. It has broad application prospects in imaging, communication, military, and monitoring. At present, research in this field is mainly focused on improving the responsivity, detection rate, response speed, and widening the response band of photodetectors. The mechanisms for photodetectors to generate photocurrent mainly include the following four: photoconductivity effect, photovoltaic effect, photothermoelectric effect, and radiation thermal effect. At present, most photodetectors are mainly based on the photovoltaic effect, that is, light generates a photogenerated potential difference on a semiconductor heterojunction or between a metal and a semiconductor contact interface. Under this mechanism, photogenerated carriers are separated by a built-in electric field. Therefore, the energy of the incident photon must be greater than the band gap width of the semiconductor material to generate photogenerated carriers, which limits the response width and response intensity of the photodetector based on this effect. Nowadays, combining multiple photoresponse mechanisms to compensate for the shortcomings of a single photoresponse mechanism is considered a solution. As a semiconductor with a large Seebeck coefficient, GaSe is expected to generate photocarriers using its photothermoelectric effect.

[0003] In addition, most of the two-dimensional material photodetectors in the industry are currently prepared by artificial transfer stacking methods, which will lead to contamination of the heterojunction interface and is not conducive to reducing leakage current in highly integrated chips. Therefore, by realizing molecular beam epitaxial growth in an ultra-high vacuum environment to prepare heterojunctions, a clean interface can be obtained, which is expected to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a photoelectric detector based on a two-dimensional GaSe and InSb heterojunction and a preparation method thereof in order to solve the above problems. Based on the photovoltaic effect brought about by the built-in electric field between the n-type InSb and p-type GaSe heterojunction and the synergistic effect between the photothermoelectric effect inside GaSe, the device has a significant light response to light in the near-infrared to mid-infrared band, and has relatively good responsivity and detection rate; the infrared photoelectric detector of the present invention has the advantages of wide band, high response, self-driving, etc., and its preparation process has strong stability and is in line with the current semiconductor industry production method, providing a new idea for the field of advanced two-dimensional material infrared photoelectric detectors.

[0005] The present invention provides a photoelectric detector based on a two-dimensional GaSe and InSb heterojunction. The photoelectric detector is a vertical layered structure, which comprises a transparent ITO electrode, a two-dimensional GaSe thin film layer, a single crystal InSb substrate and a metal bottom electrode from top to bottom.

[0006] Preferably, the single crystal InSb substrate is a single crystal with upper and lower surfaces polished on both sides, the selected doping method is n-type doping, the doping material is dispersed metal tellurium, and the thickness of the single crystal InSb substrate is 500 μm.

[0007] Preferably, the two-dimensional GaSe thin film layer has a thickness of 80-150 nm.

[0008] Preferably, the material of the metal bottom electrode is one of Au, Ag, Al or Ti, and the thickness is 50 nm.

[0009] Preferably, the transparent ITO electrode has a thickness of 100-150 nm.

[0010] A method for preparing a photodetector based on a two-dimensional GaSe and InSb heterojunction comprises the following steps: S1: Depositing a metal bottom electrode on the bottom of a single crystal InSb substrate by ultra-high vacuum thermal evaporation.

[0011] S2: A two-dimensional GaSe thin film layer is grown on the surface of a single crystal InSb substrate using ultra-high vacuum molecular beam epitaxy.

[0012] S3: Depositing a transparent ITO top electrode on the surface of the grown two-dimensional GaSe thin film layer by DC magnetron sputtering.

[0013] Preferably, the specific steps of S1 are: using a DC power supply to heat an evaporation source containing a powdered metal electrode material to 100 to 200°C, the temperature of which should not exceed the saturated vapor pressure of the powdered metal electrode material, keeping warm for 30-40 minutes, using a DC power supply to energize the heating wire on the back of the single crystal InSb substrate, and heating the single crystal InSb substrate by radiation heating to make the surface temperature of the single crystal InSb substrate reach 550°C, keeping warm for 60 minutes, then reducing the surface temperature of the single crystal InSb substrate to 250°C, and increasing the evaporation source temperature to the saturated vapor pressure of the metal material under the corresponding vacuum degree, growing for 30 minutes, then reducing the evaporation source temperature to room temperature, and maintaining the growth temperature of the single crystal InSb substrate surface for 30 minutes.

[0014] Preferably, the specific steps of S2 are: using a DC power supply to heat the evaporation source containing powdered Ga2Se3 source material to 200°C, the temperature of which should not exceed the saturated vapor pressure of the powdered Ga2Se3 source material, and keeping it warm for 40 minutes; using a DC power supply to energize the heating wire on the back of the single crystal InSb substrate, and using radiation heating to heat the single crystal InSb substrate to make the substrate surface temperature reach 550°C, and keeping it warm for 60 minutes; then reducing the surface temperature of the single crystal InSe substrate to 300°C, and raising the temperature of the evaporation source containing powdered Ga2Se3 source material to 900°C, and continuing to grow for 40 minutes; after the growth is completed, reducing the temperature of the evaporation source to room temperature, keeping the substrate surface temperature at the original growth temperature unchanged, and keeping warm for 60 minutes for annealing.

[0015] Preferably, the specific steps of S3 are: covering the surface of the two-dimensional GaSe film with a mask of the selected electrode shape, heating the entire surface of the prepared two-dimensional GaSe and InSb heterojunction to 250°C, adding the argon gas pressure to 1.5-3 Pa, adjusting the sputtering power to 20 watts, bombarding the ITO target with ionized argon ions, and depositing a transparent ITO electrode with a thickness of 100-150 nm on the surface of the two-dimensional GaSe film.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: The photoelectric detector based on the two-dimensional GaSe film and InSb heterojunction in the present invention utilizes two photoelectric response mechanisms, namely, the photovoltaic effect caused by the built-in electric field due to charge transfer at the heterojunction interface of p-type GaSe and n-type InSb, and the photothermoelectric effect caused by the temperature difference due to illumination inside the two-dimensional GaSe film. Compared with the current photoelectric detectors that generally only use a single photoelectric response mechanism of the photovoltaic effect or the photothermoelectric effect, the photoelectric detector of the present invention combines two photoelectric response mechanisms, enhances the response intensity and response band width in the infrared band, and improves the response speed of the photoelectric detector.

[0017] The photodetector of the present invention works in a self-driven mode without external bias, and spontaneously separates photogenerated carriers through the photovoltaic electromotive force at the GaSe and InSb heterojunction interface and the photothermal electromotive force generated on the GaSe surface, greatly reducing system power consumption, and is suitable for application in highly integrated array devices.

[0018] The preparation method of the present invention is carried out entirely in a vacuum environment, obtaining a clean heterojunction interface, which helps to reduce device leakage current and provides the possibility for its application in industrial chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic side view of a photodetector based on a two-dimensional GaSe thin film and InSb heterojunction according to the present invention; Figure 2 This is a current-time curve of the photodetector based on the two-dimensional GaSe film and InSb heterojunction under light with an incident wavelength of 1050 nm in Example 1 of the present invention; Figure 3 This is a current-time curve of a photodetector based on a two-dimensional GaSe thin film and an InSb heterojunction under light with an incident wavelength of 2500 nm in Example 1 of the present invention; In the figure: transparent ITO electrode 1, two-dimensional GaSe thin film layer 2, single crystal InSb substrate 3, metal bottom electrode 4. DETAILED DESCRIPTION

[0020] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0021] Example 1 The preparation method is as follows: The evaporation source containing the powdered metal Au material is heated by a DC power supply to 100 to 200°C and kept warm for 30-40 minutes. The heating wire on the back of the single crystal InSb substrate 3 is energized by a DC power supply, and the single crystal InSb substrate 3 is heated by radiation heating to make the surface temperature of the single crystal InSb substrate 3 reach 550°C and kept warm for 60 minutes. This step is to degas the metal electrode material and the single crystal InSb substrate 3, and remove the gas molecules such as water, oxygen, carbon dioxide and impurities such as polar groups adsorbed on the surface of the material by high temperature. Then, the surface temperature of the single crystal InSb substrate 3 is reduced to 250°C, and the evaporation source temperature is increased to 1000°C, grown for 30 minutes, and then the evaporation source temperature is reduced to room temperature, and the surface growth temperature of the single crystal InSb substrate 3 is maintained for 30 minutes; the evaporation source containing the powdered Ga2Se3 source material is heated by a DC power supply to 200°C, kept warm for 40 minutes, and then reduced to room temperature.

[0022] A DC power supply is used to energize the heating wire on the back side of the single crystal InSb substrate 3, and the single crystal InSb substrate 3 is heated by radiation heating to make the surface temperature of the single crystal InSb substrate 3 reach 550°C, and the temperature is kept for 60 minutes. Then, the surface temperature of the single crystal InSe substrate 3 is reduced to 300°C, and the temperature of the evaporation source containing powdered Ga2Se3 source material is increased to 900°C, and the growth is continued for 40 minutes. During this process, due to the instability of the Se atoms, a large amount of dissociation and desorption will occur, resulting in the growth of a two-dimensional GaSe film 2 with a chemical ratio of one to one. After the growth is completed, the temperature of the Ga2Se3 evaporation source is reduced to room temperature, and the surface temperature of the single crystal InSb substrate 3 is kept at the original growth temperature. It is annealed for 60 minutes to further achieve the desorption of Se atoms and improve the crystallinity of the two-dimensional GaSe film 2, thereby obtaining a large-area continuous two-dimensional GaSe film 2 with good crystallinity.

[0023] A mask of the selected electrode shape is covered on the surface of the two-dimensional GaSe film 2, the entire surface of the prepared two-dimensional GaSe and InSb heterojunction is heated to 250°C, the argon gas pressure is increased to 1.5-3 Pa, the sputtering power is adjusted to 20 W, ionized argon ions bombard the ITO target, and a transparent ITO electrode 1 with a thickness of about 120 nm is deposited on the surface of the two-dimensional GaSe film 2.

[0024] The photodetector prepared in Example 1 was tested by a photoelectric detection system, and it was found that it had significant self-driven photoresponse characteristics under near-infrared and mid-infrared wavelengths of 1050 nm and 2500 nm, such as Figure 2 and Figure 3 As shown in the figure, combined with the test results, it can be calculated that its responsivity reaches 12.6 mW / cm under near-infrared and mid-infrared light with wavelengths of 1050 nm and 2500 nm. 2 and 32.9 mW / cm 2 , the detection rate reaches 3*1014 Jones and 8*1014 Jones.

[0025] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A photodetector based on a two-dimensional GaSe and InSb heterojunction, characterized in that: The photodetector is a vertical layered structure, comprising, from top to bottom, a transparent ITO electrode (1), a two-dimensional GaSe thin film layer (2), a single crystal InSb substrate (3), and a metal bottom electrode (4).

2. A photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 1, characterized in that: The single crystal InSb substrate (3) is a single crystal with upper and lower surfaces polished on both sides, the doping method is n-type doping, the doping material is scattered metal tellurium, and the thickness of the single crystal InSb substrate is 500 μm.

3. A photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 1, characterized in that: The thickness of the two-dimensional GaSe thin film layer (2) is 80-150 nm.

4. A photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 1, characterized in that: The material of the metal bottom electrode (4) is one of Au, Ag, Al or Ti, and has a thickness of 50 nm.

5. The photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 1, characterized in that: The transparent ITO electrode (1) has a thickness of 100-150 nm.

6. A method for preparing a photodetector based on a two-dimensional GaSe and InSb heterojunction according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: depositing a metal bottom electrode (4) on the bottom of a single crystal InSb substrate (3) by ultra-high vacuum thermal evaporation; S2: growing a two-dimensional GaSe thin film layer (2) on the surface of a single crystal InSb substrate (3) by ultra-high vacuum molecular beam epitaxy; S3: Depositing a transparent ITO top electrode (1) on the surface of the grown two-dimensional GaSe thin film layer (2) by direct current magnetron sputtering.

7. The method for preparing a photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 6, characterized in that: The specific steps of S1 are: using a direct current power supply to heat an evaporation source containing a powdered metal electrode material to a temperature of 100 to 200° C., the temperature of which should not exceed the saturated vapor pressure of the powdered metal electrode material, and keeping the temperature for 30 to 40 minutes; using a direct current power supply to energize a heating wire on the back of a single crystal InSb substrate (3), and using a radiation heating method to heat the single crystal InSb substrate (3) to a surface temperature of 550° C., and keeping the temperature for 60 minutes; then reducing the surface temperature of the single crystal InSb substrate (3) to 250° C., and increasing the temperature of the evaporation source to the saturated vapor pressure of the metal material under a corresponding vacuum degree, and growing for 30 minutes; then reducing the temperature of the evaporation source to room temperature, and maintaining the surface growth temperature of the single crystal InSb substrate (3) for 30 minutes to improve the crystallinity of the metal bottom electrode (4).

8. The method for preparing a photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 6, characterized in that: The specific steps of S2 are: using a DC power supply to heat the evaporation source containing the powdered Ga2Se3 source material to 200°C, the temperature of which should not exceed the saturated vapor pressure of the powdered Ga2Se3 source material, and keeping the temperature for 40 minutes; using a DC power supply to energize the heating wire on the back of the single crystal InSb substrate (3), and using a radiation heating method to heat the single crystal InSb substrate (3) to make the surface temperature of the single crystal InSb substrate (3) reach 550°C, and keeping the temperature for 60 minutes; then reducing the surface temperature of the single crystal InSe substrate (3) to 300°C; raising the temperature of the evaporation source containing the powdered Ga2Se3 source material to 900°C, and continuing the growth for 40 minutes; after the growth is completed, reducing the temperature of the evaporation source to room temperature, keeping the surface temperature of the substrate at the original growth temperature, and keeping the temperature for 60 minutes for annealing.

9. The method for preparing a photodetector based on a two-dimensional GaSe and InSb heterojunction according to claim 6, characterized in that: The specific steps of S3 are: covering the surface of the two-dimensional GaSe film (2) with a mask plate of the selected electrode shape, heating the entire surface of the prepared two-dimensional GaSe and InSb heterojunction to 250° C., increasing the argon gas pressure to 1.5-3 Pa, adjusting the sputtering power to 20 W, bombarding the ITO target with ionized argon ions, and depositing a transparent ITO electrode (1) with a thickness of 100-150 nm on the surface of the two-dimensional GaSe film (2).

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