Interface optimization method and application of infrared detector cadmium sulfide n-type buffer layer film
By treating the cadmium sulfide film with a solution containing sulfur ions or cadmium ions, the surface defect problem caused by chemical water bath deposition is solved, and the performance and reliability of the short-wave infrared detector are improved. It is suitable for biomedical imaging, industrial inspection, national defense and security and other fields.
Patent Information
- Application Number
- CN202510743031.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-05
- Publication Date
- 2025-09-05
AI Technical Summary
In the existing technology, it is difficult to precisely control the stoichiometric ratio of sulfur and cadmium elements and the crystal growth dynamics when depositing cadmium sulfide films using the chemical water bath method, resulting in the formation of a large number of atomic vacancies on the surface and a high-density defect structure, which affects the dark current density and photoelectric conversion efficiency of the detection device.
The cadmium sulfide n-type buffer layer film is treated with a solution containing sulfur ions or cadmium ions, including cleaning, heat treatment and immersion steps, to fill sulfur vacancy defects on the film surface and optimize interface properties.
It significantly reduces the dark current density of the film, improves the performance of the detection device, improves the interface energy level matching, promotes the effective transport and extraction of photogenerated carriers, simplifies the process steps and reduces costs.
Smart Images
Figure CN120603356A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of photoelectric detectors, and in particular to an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector. Background Art
[0002] The short-wave infrared band lies between visible light and microwaves, and with its unique spectral characteristics, it exhibits multiple advantages. It has strong environmental adaptability and can penetrate atmospheric particles such as fog, smoke, and snow. It can still produce clear images in inclement weather or low-light conditions. Relying on the "night airglow" characteristic, it can achieve long-distance observation even on moonless nights by capturing atmospheric radiation. The imaging principle of short-wave infrared is based on the mechanism of reflected light, similar to visible light. Therefore, the image resolution is high and the contrast is strong. It can accurately identify object details and distinguish camouflage, and it performs outstandingly in semiconductor testing, food sorting, industrial flaw detection and other fields. In addition, short-wave infrared can be imaged through glass, supports concealed lighting, and the equipment does not require low-temperature refrigeration. It is small in size and low in power consumption, making it suitable for many scenarios such as industry, security, and medical care.
[0003] In the field of thin-film photovoltaics, cadmium sulfide (CdS) has become a key material in various thin-film photovoltaic technologies due to its advantages, including high electron mobility, ideal spectral response, and low-temperature fabrication process. As a wide-bandgap semiconductor, it plays a vital role in mainstream photovoltaic systems such as cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and copper zinc tin sulfide (CZTS). Notably, CIGS and CdTe thin-film technologies, currently the most industrialized, have achieved conversion efficiencies exceeding 22%. The cost and environmental benefits of the CZTS system are also significant. In device configurations, CdS exhibits differentiated functional properties: in CdTe heterojunctions, it serves as an n-type functional layer, fulfilling carrier transport responsibilities; in CIGS and CZTS systems, the n-type buffer layer effectively modulates lattice compatibility and optimizes bandgap alignment. Recent research advances demonstrate the material's outstanding performance in the emerging field of planar perovskite cells, demonstrating its potential as an alternative to traditional TiO2 as an electron transport layer, particularly in improving thin-film crystal quality.
[0004] The synthesis process of CdS materials is diverse, covering a variety of technical paths such as solution method, sputtering method, evaporation method and sonochemical synthesis. Among them, chemical bath deposition (CBD) has become the mainstream process choice for the preparation of CdS and its composite materials due to its precise control capabilities and economic advantages. However, this technology still has significant limitations: it is difficult to accurately control the stoichiometric ratio of sulfur and cadmium elements and the crystal growth dynamics during the deposition process, resulting in the formation of a large number of atomic vacancies on the surface of the material and a high-density defect structure. These lattice defects can act as capture centers for photogenerated carriers, causing surface lattice reconstruction and electron-hole recombination surges, which have a significant negative impact on the dark current density of the detection device and significantly weaken the photoelectric conversion efficiency of the material. Summary of the Invention
[0005] The embodiments of the present application provide an interface optimization method and application for a cadmium sulfide n-type buffer layer film of an infrared detector. By treating the cadmium sulfide n-type buffer layer film with a solution containing sulfur ions or cadmium ions, the surface atomic vacancies caused by chemical water bath deposition are reduced, thereby improving the interface properties of the cadmium sulfide film and optimizing the overall performance of the detection device. The method has very broad development prospects.
[0006] In order to solve the above-mentioned technical problems, in the first aspect, an embodiment of the present application provides an interface optimization method for a cadmium sulfide n-type buffer layer film of an infrared detector, comprising the following steps: first, forming a cadmium sulfide n-type buffer layer film on an absorption layer; then, cleaning the cadmium sulfide n-type buffer layer film and then drying it; next, heat-treating the dried cadmium sulfide n-type buffer layer film; then, fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions; next, at a certain temperature, immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions for a period of time; finally, removing the immersed cadmium sulfide n-type buffer layer film.
[0007] In some exemplary embodiments, forming a cadmium sulfide n-type buffer layer thin film on the absorber layer includes: depositing the cadmium sulfide n-type buffer layer thin film on the absorber layer using a chemical water bath method.
[0008] In some exemplary embodiments, the solution containing sulfur ions includes one of a thiourea solution, a sodium sulfide solution, or an ammonium polysulfide solution; and the solution containing cadmium ions includes a cadmium chloride solution or a cadmium nitrate solution.
[0009] In some exemplary embodiments, the concentration of the solution containing sulfur ions or cadmium ions is 0.1 mol / L to 1.5 mol / L.
[0010] In some exemplary embodiments, the temperature of the solution containing sulfur ions or cadmium ions is 50°C to 80°C.
[0011] In some exemplary embodiments, after removing the soaked cadmium sulfide n-type buffer layer film, the method further includes: sequentially washing and drying the soaked cadmium sulfide film.
[0012] In some exemplary embodiments, the washing process includes: using deionized water as a detergent to wash the soaked cadmium sulfide film for a washing time of 15 seconds to 30 seconds.
[0013] In some exemplary embodiments, the dried cadmium sulfide n-type buffer layer film is heat-treated, including: heat-treating the dried cadmium sulfide n-type buffer layer film in an air atmosphere and keeping the temperature; the heat treatment temperature is 120° C. to 160° C., and the holding time is 2 minutes.
[0014] In a second aspect, the embodiments of the present application further provide an interface-optimized cadmium sulfide buffer layer film, which is produced using the interface optimization method for the infrared detector cadmium sulfide n-type buffer layer film as described in the above embodiments.
[0015] In a third aspect, an embodiment of the present application further provides an application of the interface-optimized cadmium sulfide semiconductor film as described in the above embodiment in a short-wave infrared photodetector.
[0016] The technical solution provided by the embodiments of the present application has at least the following advantages:
[0017] The present application provides an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector. The method comprises the following steps: first, forming a cadmium sulfide n-type buffer layer film on an absorption layer; then, cleaning the cadmium sulfide n-type buffer layer film and then drying it; next, heat-treating the dried cadmium sulfide n-type buffer layer film; then, fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions; next, immersing the heat-treated cadmium sulfide n-type buffer layer film in the solution containing sulfur ions or cadmium ions for a period of time at a certain temperature; and finally, removing the immersed cadmium sulfide n-type buffer layer film.
[0018] The core goal of this application is to develop an interface optimization technology and its application scheme for cadmium sulfide (CdS) n-type buffer layer film in CCZTSe short-wave infrared detector. 2+) chemical solution to the surface of the CdS film, which can effectively repair the surface atomic vacancy defects generated during the chemical water bath deposition process. The specific mechanism of action is that sulfur and cadmium ions can directionally fill the sulfur vacancies or cadmium vacancies in the CdS lattice, while passivating the dangling bonds and unsaturated coordination atoms on the surface of the film, thereby significantly reducing the interface state density and improving the interface energy level matching. This interface modification strategy can not only enhance the crystallization quality and surface smoothness of the CdS film, but also inhibit the interfacial charge recombination phenomenon and promote the effective transport and extraction of photogenerated carriers. Experiments show that the detection device after optimized treatment has achieved improvements in key performance indicators such as dark current and detection rate, and the process has the characteristics of simple operation, low cost and strong compatibility, providing a reliable technical path for the high performance and industrial application of short-wave infrared detectors, and showing important application value and broad market prospects in the fields of biomedical imaging, industrial detection and national defense security.
[0019] The present application provides an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector. On the one hand, the present application achieves optimized control of the film interface by subjecting the cadmium sulfide semiconductor film to an infiltration treatment with a solution containing sulfur ions or cadmium ions. This method can effectively fill the sulfur vacancy defects on the surface of the film, significantly improving its surface state, thereby effectively reducing the dark current density of the film and the performance of short-wave infrared detection devices. On the other hand, the raw materials required for this optimization method are easily available, the process steps are simple, the equipment requirements are low, and it has good potential for industrial production. This technology has important practical value for improving the performance of copper cadmium zinc tin selenide (CCZTSe) short-wave infrared detectors. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] One or more embodiments are exemplarily described by the pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute proportional limitations.
[0021] Figure 1 A schematic flow chart of an interface optimization method for a cadmium sulfide n-type buffer layer film of an infrared detector provided in an embodiment of the present application.
[0022] Figure 2 Schematic diagram of the structure of the CCZTSe short-wave infrared detection device provided in an embodiment of the present application.
[0023] Figure 3 The Cu2Cd provided in the embodiment of this application x Zn 1-x SnSe4 shortwave infrared detector production flow chart.
[0024] Figure 4 This is an AFM image of CdS before interface optimization provided in an embodiment of the present application.
[0025] Figure 5 This is an AFM image of CdS after interface optimization provided in an embodiment of the present application.
[0026] Figure 6 This is the IV curve of the device provided in the embodiment of the present application before and after interface optimization.
[0027] Figure 7 This is a comparison chart of the quantum efficiencies of the untreated device group and the thiourea solution-treated device group provided in the examples of the present application.
[0028] Figure 8 The capacitance-voltage (CV) and driver-level capacitance analysis (DLCP) measurements provided in the embodiments of the present application provide interface defect density (NIT) diagrams.
[0029] Figure 9 This is a Raman spectrum diagram provided in the examples of this application. DETAILED DESCRIPTION
[0030] As can be seen from the background art, the existing synthesis process of CdS materials has significant limitations, which have a significant negative impact on the dark current density of the detection device and significantly weaken the photoelectric conversion efficiency of the material.
[0031] In order to solve the above technical problems, the embodiment of the present application provides an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector, the method comprising the following steps: first, forming a cadmium sulfide n-type buffer layer film on an absorption layer; then, cleaning the cadmium sulfide n-type buffer layer film and then drying it; next, heat-treating the dried cadmium sulfide n-type buffer layer film; then, fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions; next, immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions for a period of time at a certain temperature; finally, removing the immersion cadmium sulfide n-type buffer layer film. The interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector provided by the present application, by treating the cadmium sulfide n-type buffer layer film with a solution containing sulfur ions or cadmium ions, reduces the surface atomic vacancies caused by chemical water bath deposition, thereby improving the interface properties of the cadmium sulfide film and optimizing the overall performance of the detection device, and has a very broad development prospect.
[0032] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.
[0033] See Figure 1 The present invention provides an interface optimization method for an infrared detector cadmium sulfide n-type buffer layer thin film, comprising the following steps:
[0034] Step S101 : forming a cadmium sulfide n-type buffer layer thin film on the absorption layer.
[0035] Step S102 : cleaning the cadmium sulfide n-type buffer layer film and then drying it.
[0036] Step S103 , heat-treating the dried cadmium sulfide n-type buffer layer film.
[0037] Step S104 , fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions.
[0038] Step S105 : Immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions for a period of time at a certain temperature.
[0039] Step S106 , taking out the cadmium sulfide n-type buffer layer film after the soaking.
[0040] The interface optimization method of the cadmium sulfide n-type buffer layer film of the infrared detector provided in the embodiment of the present application is a surface modification method of the cadmium sulfide n-type buffer layer film used in the copper cadmium zinc tin selenium (CCZTSe) short-wave infrared detector. The specific implementation method of the surface modification method includes: placing the cadmium sulfide buffer layer film prepared by the chemical bath deposition method (CBD) in a chemical solution rich in sulfur ions for full immersion. By providing sulfur ions to fill the sulfur vacancies on the surface of the cadmium sulfide buffer layer film, the optimization and regulation of the interface characteristics of the cadmium sulfide buffer layer film is achieved. By constructing a sulfur ion replenishment mechanism, this technical solution can effectively passivate surface defects and fill sulfur vacancies, thereby obtaining a high-quality film surface with a better lattice structure. After characterization and verification, the modified cadmium sulfide buffer layer film exhibits a significantly improved surface flatness and significantly reduces the dark current density of the detection device, thereby effectively optimizing the performance of the copper cadmium zinc tin selenium (CCZTSe) short-wave infrared detector.
[0041] In some embodiments, step S101 forms a cadmium sulfide n-type buffer layer thin film on the absorber layer, including: depositing the cadmium sulfide n-type buffer layer thin film on the absorber layer using a chemical water bath method, wherein the absorber layer is a p-type multi-compound absorber layer.
[0042] The p-type multi-compound absorption layer material used in the device of this application is a new narrow-bandgap copper-based thin film compound semiconductor material Cu2Cd x Zn (1-x) SnSe4, the n-type buffer layer material is a cadmium sulfide film after solution treatment. The short-wave infrared detector structure is as follows Figure 2As shown in the figure. 1 is a soda-lime glass substrate. 2 is a molybdenum metal layer deposited by magnetron sputtering on the soda-lime glass substrate, which serves as a back electrode for deriving electrical signals. 3 is an absorption layer of p-type narrow-bandgap semiconductor material grown by co-evaporation. 4 is a cadmium sulfide film deposited by a solution-treated chemical bath method. 5 is an intrinsic zinc oxide / Al-doped zinc oxide (i-ZnO / AZO) transparent conductive window layer film grown by magnetron sputtering. 6 is a Ni-Al-Ni metal electrode deposited by electron beam evaporation.
[0043] The technical implementation means included in this application are mainly reflected in the surface treatment of semiconductor films. The process flow is as follows Figure 3 shown.
[0044] First, a molybdenum back electrode was deposited using DC magnetron sputtering: a soda-lime glass substrate was placed in a vacuum chamber and held at 200°C for 1 hour. The substrate was then transferred to a coating chamber and purged with argon. The loose molybdenum layer was sputtered in the first step, with a power of 900W and a sample holder speed of 0.2m / min for eight revolutions. The dense molybdenum layer was then sputtered in the second step, with a power of 5000W and a sample holder speed of 0.2m / min for two revolutions. Finally, a 1000nm thick molybdenum back electrode was obtained.
[0045] Next, a CCZTSe absorber layer is grown using a co-evaporation method: a molybdenum back electrode substrate is placed in a multi-source co-evaporation deposition apparatus. The vacuum is maintained at 10-5 Pa. The temperatures of the five sources (Cu, Zn, Sn, Se, and Cd) are adjusted, and the baffle is opened once the temperature stabilizes. The CCZTSe precursor is grown for 20 minutes. The precursor is then removed and annealed at 420-490°C to allow grain growth and obtain the CCZTSe absorber layer, which is approximately 1500 nm thick.
[0046] It should be noted that the substrate used in this application is not limited to soda-lime glass, but can also be directly grown on CMOS chips, low-resistance silicon wafers, and fluorine-doped tin oxide FTO glass. It has a wide range of applications and high commercial potential. The material of the back electrode layer used in this application includes at least one of molybdenum, aluminum, silver, and gold, but is not limited thereto. The material of the p-type absorption layer used in this application can be other multi-component absorption layer materials such as CIGS and CdTe. This application mainly optimizes the buffer layer. Similar effects can be achieved by using a system with similar device structure and buffer layer material.
[0047] Next, a chemical water bath method was used to prepare a CdS buffer layer: the CCZTSe absorption layer was placed in the center of the reaction vessel, with the absorption layer facing downward. The prepared cadmium sulfate and ammonia mixed solution, thiourea solution, and ultrapure water were poured into the reaction vessel. The water bath temperature was maintained at 67°C and stirred for 9 minutes and 30 seconds. After the reaction, the CdS surface was rinsed with ultrapure water, dried, and placed in a 120°C oven for 2 minutes to obtain a CdS buffer layer with a thickness of approximately 50nm. Subsequently, a 1mol / L thiourea solution (temperature 60 degrees) was added to infiltrate for 30-60 minutes, and then the surface of the CdS was rinsed with ultrapure water and dried to obtain a cadmium sulfide film with optimized interface.
[0048] Then, the i-ZnO / AZO transparent conductive window layer was sputtered by RF magnetron sputtering: the CdS buffer layer was placed in the i-ZnO / AZO sputtering chamber, argon and oxygen (argon-oxygen flow ratio of 20 to 1) were introduced, and the i-ZnO target was sputtered on the sample for 4 circles, 4 circles and 16 circles at powers of 120W, 220W and 350W, respectively; then the oxygen was turned off, hydrogen was introduced (argon-hydrogen flow ratio of 20 to 1.5), and the AZO target was sputtered on the sample for 14 circles at a power of 500W to finally obtain the i-ZnO / AZO window layer.
[0049] Then, the Ni-Al-Ni metal electrode was deposited by electron beam deposition: the window layer i-ZnO / AZO was covered with a mask and moved into the electron beam deposition chamber, and the vacuum was maintained at 10 -3 Below Pa, the thickness of the first Ni layer is 100nm, the thickness of the second Al layer is 1000nm, and the thickness of the last Ni layer is 100nm, thus obtaining a Ni-Al-Ni metal electrode.
[0050] It should be noted that the material of the surface electrode layer used in this application is not limited to Ni-Al-Ni, and can be copper, gold, silver, chromium, aluminum, etc. The transparent conductive window layer material used in this application is at least one of zinc aluminum oxide, indium tin oxide, and indium zinc oxide, but is not limited thereto.
[0051] Finally, the device was photolithographically segmented: the sample surface was spin-coated with negative photoresist, pre-baked at 150°C for 1 minute, exposed for 30 seconds, post-baked at 100°C for 1 minute, developed for 20 seconds, etched with dilute hydrochloric acid solution for 40 seconds, and then de-bonded with acetone. Finally, the sample surface was segmented into multiple devices with a device size of 2.5 mm × 2.5 mm.
[0052] In some embodiments, the solution containing sulfur ions in step S104 and step S105 includes one of thiourea solution, sodium sulfide solution, or ammonium polysulfide solution; and the solution containing cadmium ions includes cadmium chloride solution or cadmium nitrate solution.
[0053] In some embodiments, the concentration of the solution containing sulfur ions or cadmium ions in step S104 and step S105 is 0.1 mol / L to 1.5 mol / L. Preferably, the concentration of the solution containing sulfur ions or cadmium ions is 1 mol / L.
[0054] In some embodiments, the temperature of the solution containing sulfur ions or cadmium ions in step S105 is 50° C. to 80° C., and the immersion time is 15 min to 60 min. Preferably, the temperature of the solution containing sulfur ions or cadmium ions is 70° C., and the immersion time is 60 min.
[0055] In some embodiments, after removing the soaked cadmium sulfide n-type buffer layer film in step S106 , the method further includes: sequentially washing and drying the soaked cadmium sulfide film.
[0056] In some embodiments, the washing process includes: using deionized water as a detergent to wash the soaked cadmium sulfide film for 15 seconds to 30 seconds.
[0057] In some embodiments, step S103 heat-treats the dried cadmium sulfide n-type buffer layer film, including: heat-treating the dried cadmium sulfide n-type buffer layer film in an air atmosphere and keeping it warm; the heat treatment temperature is 120° C. to 160° C., and the holding time is 2 minutes.
[0058] AFM image of CdS before interface optimization Figure 4 As shown in the AFM image of CdS after interface optimization, Figure 5 As shown, by comparison Figure 4 and Figure 5 It can be seen that the surface flatness of the buffer layer film is significantly improved after treatment with the sulfur-containing solution, indicating that the optimization method provided in this application can effectively fill the sulfur vacancy defects on the surface of the film and significantly improve its surface state, thereby effectively reducing the dark current density of the film and the performance of the short-wave infrared detection device.
[0059] Figure 6 The IV curves of the CdS electrode before and after interface optimization are shown. The test system is a 1 mol / L CH4N2S solution, ranging from -0.5 V to 1 V. The digital source meter used for this characterization test is a KEITHLEY-2400, and the temperature is 26°C. Figure 6 Device 1 represents the device group corresponding to the CdS thin film without any treatment, and device 2 represents the device group corresponding to the CdS thin film after being immersed in CH4N2S solution. Figure 6 It can be seen that the dark current density of the device group corresponding to the CdS film treated with CH4N2S solution is significantly lower than that of the device group corresponding to the untreated CdS film, which proves that the treatment with sulfur ion solution does improve the dark current density of the device and effectively improves the device performance.
[0060] After experiments, the components of this application have been found to have intact contacts, normal resistance between the upper and lower poles of the device, and meet the designed detection function. After a series of standard test characterizations, the experimental results are in line with expectations.
[0061] AFM comparison of cadmium sulfide buffer layer film after solution treatment is shown in Figure 4 and Figure 5 , it can be seen that the surface flatness is improved. The IV curve comparison of CdS electrode before and after interface optimization is shown in Figure 6 , it can be seen that the dark current is reduced by 20%-30%. Device QE comparison is shown in Figure 7 , it can be seen that the QE of the sample has a positive improvement trend. The interface defect density (NIT) is obtained by capacitance-voltage (CV) and driver level capacitance analysis (DLCP) tests, see Figure 8 , it can be seen that the interface state density of the sample is significantly reduced. Raman (RAMAN) test of cadmium sulfide film before and after treatment is shown in Figure 9 , it can be seen that the high-order phonon ratio of the sample is improved, proving that the crystal quality of the sample is improved.
[0062] The present application provides a surface treatment process for cadmium sulfide thin films. By treating the cadmium sulfide thin films with a solution containing sulfur ions or cadmium ions, the surface flatness of the cadmium sulfide thin films can be significantly improved, the device heterojunction interface quality can be improved, and the interface state density of the device can be effectively improved, thereby reducing the dark current density. Moreover, the Cu2Cd x Zn 1-x SnSe4 (where 0≤x<1) quinary compound p-type layer material is a new narrow bandgap semiconductor material. Grown in vacuum equipment using the co-evaporation method, it boasts low cost. By manipulating the Cd component in the precursor, the device bandgap width can be controlled, making it a narrow bandgap semiconductor material. This material also exhibits a broad absorption spectrum, with the device absorption edge reaching 1700nm.
[0063] The embodiments of the present application also provide an interface-optimized cadmium sulfide buffer layer film, which is produced using the interface optimization method for the infrared detector cadmium sulfide n-type buffer layer film as described in the above embodiments.
[0064] In addition, an embodiment of the present application also provides an application of the interface-optimized cadmium sulfide semiconductor film described in the above embodiment in a short-wave infrared photodetector.
[0065] Compared with the prior art, the interface optimization method and application of the cadmium sulfide n-type buffer layer film for infrared detectors provided in this application have the following advantages:
[0066] Current surface treatment methods primarily involve treating cadmium sulfide films at elevated temperatures using special atmospheres such as cadmium chloride or hydrogen sulfide, or using ultraviolet light combined with ozone cleaning. However, these treatments are not suitable for the infrared detectors described in this invention. Experimental verification has shown that CCZTSe absorber films have poor tolerance to high temperatures and cannot withstand the temperature and time requirements of these treatments. Furthermore, these gases are highly toxic and dangerous. Furthermore, ultraviolet light and ozone cleaning methods require high experimental equipment and conditions, making them difficult to implement on a large scale.
[0067] The solution-based method for treating a cadmium sulfide buffer layer disclosed herein uses a solution to surface treat a cadmium sulfide film. This method is gentle, requires minimal equipment, and can be widely adopted. Furthermore, the method is simple and convenient to operate, without negatively impacting the absorber layer. The surface-treated buffer layer exhibits a superior lattice structure, improved surface flatness, lower interface state defect density, and lower dark current.
[0068] Based on the above technical solution, the present application provides an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector. The method includes the following steps: first, forming a cadmium sulfide n-type buffer layer film on an absorption layer; then, cleaning the cadmium sulfide n-type buffer layer film and then drying it; next, heat-treating the dried cadmium sulfide n-type buffer layer film; then, fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions; next, at a certain temperature, immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions for a period of time; finally, removing the immersed cadmium sulfide n-type buffer layer film.
[0069] The present application provides an interface optimization method and application of a cadmium sulfide n-type buffer layer film for an infrared detector. On the one hand, the present application achieves optimized control of the film interface by subjecting the cadmium sulfide semiconductor film to an infiltration treatment with a solution containing sulfur ions or cadmium ions. This method can effectively fill the sulfur vacancy defects on the surface of the film, significantly improving its surface state, thereby effectively reducing the dark current density of the film and the performance of short-wave infrared detection devices. On the other hand, the raw materials required for this optimization method are easily available, the process steps are simple, the equipment requirements are low, and it has good potential for industrial production. This technology has important practical value for improving the performance of copper cadmium zinc tin selenide (CCZTSe) short-wave infrared detectors.
[0070] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be subject to the scope defined in the claims.
Claims
1. A method for optimizing the interface of a cadmium sulfide n-type buffer layer film for an infrared detector, characterized in that: The following steps are involved: forming a cadmium sulfide n-type buffer layer thin film on the absorption layer; cleaning the cadmium sulfide n-type buffer layer film and then drying it; performing heat treatment on the dried cadmium sulfide n-type buffer layer film; fully immersing the heat-treated cadmium sulfide n-type buffer layer film in a solution containing sulfur ions or cadmium ions; At a certain temperature, the heat-treated cadmium sulfide n-type buffer layer film is immersed in a solution containing sulfur ions or cadmium ions for a period of time; The cadmium sulfide n-type buffer layer film is taken out after being soaked.
2. The interface optimization method of the cadmium sulfide n-type buffer layer thin film of the infrared detector according to claim 1, characterized in that: The step of forming a cadmium sulfide n-type buffer layer thin film on the absorption layer comprises: A cadmium sulfide n-type buffer layer film is deposited on the absorber layer by a chemical water bath method.
3. The interface optimization method of the infrared detector cadmium sulfide n-type buffer layer film according to claim 1, characterized in that: The solution containing sulfur ions includes one of thiourea solution, sodium sulfide solution or ammonium polysulfide solution; and the solution containing cadmium ions includes cadmium chloride solution or cadmium nitrate solution.
4. The interface optimization method of the infrared detector cadmium sulfide n-type buffer layer film according to claim 1, characterized in that: The concentration of the solution containing sulfur ions or cadmium ions is 0.1 mol / L to 1.5 mol / L.
5. The interface optimization method of the cadmium sulfide n-type buffer layer thin film of the infrared detector according to claim 1, characterized in that: The temperature of the solution containing sulfur ions or cadmium ions is 50°C to 80°C.
6. The method for optimizing the interface of a cadmium sulfide n-type buffer layer thin film for an infrared detector according to claim 1, characterized in that: After removing the cadmium sulfide n-type buffer layer film after the soaking, the method further includes: The cadmium sulfide film after infiltration is sequentially washed and dried.
7. The method for optimizing the interface of a cadmium sulfide n-type buffer layer thin film for an infrared detector according to claim 6, characterized in that: The washing process includes: using deionized water as a detergent to wash the soaked cadmium sulfide film, and the washing time is 15s to 30s.
8. The interface optimization method of the cadmium sulfide n-type buffer layer thin film of the infrared detector according to claim 1, characterized in that: The dried cadmium sulfide n-type buffer layer film is subjected to heat treatment, including: heat-treating the dried cadmium sulfide n-type buffer layer film in an air atmosphere and keeping the temperature; The heat treatment temperature is between 120°C and 160°C, and the holding time is 2 minutes.
9. An interface-optimized cadmium sulfide buffer layer film, characterized in that: The cadmium sulfide n-type buffer layer thin film is prepared by using the interface optimization method of the infrared detector according to any one of claims 1 to 8.
10. Use of the interface-optimized cadmium sulfide semiconductor film according to claim 9 in a short-wave infrared photodetector.