An infrared detector and its preparation method

Abstract

This invention discloses an infrared detector and its fabrication method, comprising: an N-type thin film layer, a mercury sulfide quantum dot layer, a P-type thin film layer, and a top electrode; the mercury sulfide quantum dot layer is disposed between the N-type and P-type thin film layers, forming a p-on-n type double heterojunction; the top electrode is disposed on the side of the p-on-n type double heterojunction near the P-type thin film layer, and is fabricated by magnetron sputtering. During the fabrication of the top electrode, the P-type thin film layer protects the mercury sulfide quantum dot layer. The top electrode is fabricated as an ITO transparent electrode using magnetron sputtering. While ensuring light transmission, the P-type thin film layer protects the mercury sulfide quantum dot layer, buffering it and preventing high-energy particles from damaging the quantum dot layer during magnetron sputtering fabrication, thereby reducing interface defects and dark current within the infrared detector.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detection technology, and specifically relates to an infrared detector and its preparation method. Background Technology

[0002] The human eye's light-sensing range is only between 300 and 800 nm, while infrared detectors can respond to infrared radiation exceeding this range by generating a photoelectric response, enabling detection and imaging of wavelengths beyond the visible light spectrum (λ>800 nm). Even in environments without visible light, infrared detectors can clearly display objects. Therefore, infrared photodetectors have been widely used in various fields such as industrial inspection, meteorological remote sensing, medical imaging, and aerospace exploration. Traditional infrared detection materials typically rely on single-crystal semiconductors such as indium antimonide (InSb), indium gallium arsenide (InGaAs), and mercury cadmium telluride (HgCdTe). However, the molecular beam epitaxy (MBE) growth process for these materials is costly, and the manufacturing process often requires complex flip-chip bonding, resulting in high device manufacturing costs and limiting their widespread application. In recent years, the rapid development of novel semiconductor materials, primarily low-dimensional materials, has brought new opportunities for innovation in infrared photodetector technology. Among them, mercury thiosulfate colloidal quantum dots have made significant progress in the development of low-cost, high-performance infrared detectors due to their advantages such as a broad infrared tuning spectrum, simple synthesis process, and easy integration with silicon-based readout circuits.

[0003] Currently, many high-performance PN junction-type mercury sulfide colloidal quantum dot detectors employ a bottom-illuminated p-on-n structure. In these structures, the p-type layer is typically formed by spin-coating an Ag₂Te quantum dot layer onto the surface of the mercury sulfide quantum dot, followed by spin-coating mercuric chloride, and then forming a silver-doped mercuric telluride quantum dot layer through a cation exchange reaction. During this process, silver ions may diffuse into the mercury sulfide quantum dot film, and this diffusion is uncontrollable, potentially disrupting the stability of the PN junction and significantly affecting the detector's performance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an infrared detector and its fabrication method.

[0005] In a first aspect, this application provides an infrared detector, comprising: an N-type thin film layer, a mercury thiosulfate quantum dot layer, a P-type thin film layer, and a top electrode;

[0006] The mercury sulfide quantum dot layer is disposed between the N-type thin film layer and the P-type thin film layer, and the N-type thin film layer, the mercury sulfide quantum dot layer and the P-type thin film layer are used to form a p-on-n type double heterojunction;

[0007] The top electrode is disposed on the side of the p-on-n type double heterojunction near the p-type thin film layer. The top electrode is prepared by magnetron sputtering. During the preparation of the top electrode, the p-type thin film layer is used to protect the mercury thiosulfate quantum dot layer.

[0008] This also includes: substrate;

[0009] The bottom electrode is disposed on the substrate.

[0010] The p-on-n type double heterojunction is disposed between the bottom electrode and the top electrode, and the bottom electrode and the top electrode are used to connect negative and positive charges to enable current conduction.

[0011] The N-type thin film layer includes either ZnO or SnO2.

[0012] The mercury sulfide quantum dot layer includes any one of HgSe quantum dots, HgS quantum dots, and HgTe quantum dots with an absorption cutoff wavelength of 1100 nm to 4000 nm.

[0013] The P-type thin film layer includes ZnTe.

[0014] The bottom electrode includes any one or more of Au and indium tin oxide (ITO);

[0015] The top electrode is an ITO transparent electrode.

[0016] The thickness of the mercury sulfide quantum dot layer is greater than that of the N-type thin film layer and the P-type thin film layer.

[0017] Secondly, this application provides a method for preparing an infrared detector, the method comprising:

[0018] Preparation of N-type thin film layers:

[0019] A mercury thiogroup quantum dot layer was prepared on the N-type thin film layer;

[0020] A P-type thin film layer is prepared on the mercury sulfide quantum dot layer; the N-type thin film layer, the mercury sulfide quantum dot layer, and the P-type thin film layer are used to form a p-on-n type double heterojunction.

[0021] A top electrode is fabricated on the side of the P-type thin film layer away from the N-type thin film layer using a magnetron sputtering process.

[0022] The method further includes:

[0023] Provide substrate;

[0024] Fabricate the bottom electrode on the substrate;

[0025] The steps for preparing the N-type thin film layer include:

[0026] The N-type thin film layer is prepared by depositing ZnO or SnO2 on the side of the bottom electrode away from the substrate;

[0027] The preparation of a P-type thin film layer on the mercury sulfide quantum dot layer includes:

[0028] A ZnTe thin film was deposited on the mercury thiocyanate quantum dot layer.

[0029] The step of preparing a mercury sulfide quantum dot layer on the N-type thin film layer includes:

[0030] Preparation of quantum dot solutions;

[0031] Liquid-phase ligand exchange was performed on the quantum dot solution using a mixture of HgCl2, mercaptoethanol, and n-butylamine in N,N-dimethylformamide.

[0032] The solution after liquid phase ligand exchange was precipitated with ethanol, and the precipitate was then prepared into a high-concentration coating solution of N,N-dimethylformamide and n-butylamine.

[0033] A mercury thiogroup quantum dot layer was prepared on the N-type thin film layer using a coating solution;

[0034] The preparation of the quantum dot solution includes:

[0035] HgTe quantum dot solution was synthesized by adding the tellurium precursor to a solution of mercuric chloride oleylamine containing long-chain ligands; or

[0036] n-type HgSe quantum dot solution was synthesized by injecting selenourea dissolved in oleylamine into a long-chain ligand solution of mercuric chloride oleylamine; or

[0037] n-type HgS quantum dot solutions were synthesized by injecting a sulfur source dissolved in oleylamine into a long-chain ligand solution of mercuric oleylamine chloride.

[0038] The thickness of the mercury sulfide quantum dot layer is greater than that of the N-type thin film layer and the P-type thin film layer.

[0039] The thickness of the N-type thin film layer is 20–200 nm; the thickness of the mercury thiosulfate quantum dot layer is 200–500 nm; and the thickness of the P-type thin film layer is 10–100 nm.

[0040] The infrared detector of this application includes: an N-type thin film layer, a mercury sulfide quantum dot layer, a P-type thin film layer, and a top electrode. The mercury sulfide quantum dot layer is disposed between the N-type thin film layer and the P-type thin film layer, and the N-type thin film layer, the mercury sulfide quantum dot layer, and the P-type thin film layer are used to form a p-on-n type double heterojunction. The top electrode is disposed on the side of the p-on-n type double heterojunction close to the P-type thin film layer. The top electrode is fabricated by magnetron sputtering, and during the fabrication of the top electrode, the P-type thin film layer is used to protect the mercury sulfide quantum dot layer. The top electrode is fabricated as an ITO transparent electrode using magnetron sputtering. While ensuring light transmission, the P-type thin film layer protects the mercury sulfide quantum dot layer, buffering it so that high-energy particles cannot damage the mercury sulfide quantum dot layer during the fabrication of the top electrode by magnetron sputtering, thereby reducing interface defects in the infrared detector and lowering dark current. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of a p-on-n type mercury thiocyanate colloidal quantum dot infrared detector in the prior art.

[0043] Figure 2 This is a schematic diagram of the structure of the first embodiment of the infrared detector according to this application;

[0044] Figure 3 This is a schematic diagram of the structure of the first embodiment of the infrared detector according to this application. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Most existing high-performance PN junction type mercury thiocarbamate colloidal quantum dot detectors employ a bottom-illuminated p-on-n structure, such as... Figure 1 As shown, the p-type layer in the device structure ( Figure 1Most silver telluride quantum dot layers are obtained by spin-coating an Ag₂Te quantum dot layer onto a mercury sulfide quantum dot surface, followed by spin-coating mercuric chloride and cation exchange to form silver-doped mercury telluride quantum dots. During this p-type layer fabrication process, silver ions tend to diffuse into the mercury sulfide colloidal quantum dot layer film within the device structure. This diffusion is uncontrollable for forming a stable PN junction and severely affects the performance of the infrared detector.

[0047] In view of this, this application provides an infrared detector comprising: an N-type thin film layer, a mercury sulfide quantum dot layer, a P-type thin film layer, and a top electrode; the mercury sulfide quantum dot layer is disposed between the N-type thin film layer and the P-type thin film layer, and the N-type thin film layer, the mercury sulfide quantum dot layer, and the P-type thin film layer are used to form a p-on-n type double heterojunction; the top electrode is disposed on the side of the p-on-n type double heterojunction close to the P-type thin film layer, the top electrode is prepared by magnetron sputtering, and during the preparation of the top electrode, the P-type thin film layer is used to protect the mercury sulfide quantum dot layer.

[0048] The infrared detector and its fabrication method of this application are described below with reference to the specific accompanying drawings.

[0049] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a first embodiment of the infrared detector according to this application. The infrared detector includes: an N-type thin film layer 30, a mercury sulfide quantum dot layer 40, a P-type thin film layer 50, and a top electrode 60. The mercury sulfide quantum dot layer 40 is disposed between the N-type thin film layer 30 and the P-type thin film layer 50. The N-type thin film layer 30, the mercury sulfide quantum dot layer 40, and the P-type thin film layer 50 are used to form a p-on-n type double heterojunction. The top electrode 60 is disposed on the side of the p-on-n type double heterojunction near the P-type thin film layer 50. The top electrode 60 is fabricated by magnetron sputtering, and during the fabrication of the top electrode, the P-type thin film layer is used to protect the mercury sulfide quantum dot layer. Specifically, during the fabrication of the top electrode 60 by magnetron sputtering, the P-type thin film layer 50 serves to buffer the mercury sulfide quantum dot layer 40, preventing high-energy particles from damaging the mercury sulfide quantum dot layer 40 during magnetron sputtering, thereby reducing interface defects in the infrared detector and lowering dark current.

[0050] In this embodiment, the N-type thin film layer 30 is also used for electron transport, and the P-type thin film layer 50 is used for hole transport.

[0051] Furthermore, the infrared detector also includes a substrate 10 and a bottom electrode 20; wherein the bottom electrode 20 is disposed on the substrate 10, and the p-on-n type double heterojunction is disposed between the bottom electrode 20 and the top electrode 60, and the bottom electrode 20 and the top electrode 60 are used to connect negative and positive charges to conduct current.

[0052] In one specific embodiment, the infrared detector comprises, from bottom to top: a substrate 10, a bottom electrode 20, an N-type thin film layer 30, a mercury sulfide quantum dot layer 40, a P-type thin film layer 50, and a top electrode 60. The N-type thin film layer 30, the mercury sulfide quantum dot layer 40, and the P-type thin film layer 50 are used to form a p-on-n type double heterojunction. The bottom electrode 20 and the top electrode 60 are used to connect negative and positive charges, respectively, to conduct current. Specifically, the bottom electrode 20 is used to connect negative charges, and the top electrode 60 is used to connect positive charges. The substrate 10 supports the bottom electrode 20, the N-type thin film layer 30, the mercury sulfide quantum dot layer 40, the P-type thin film layer 50, and the top electrode 60.

[0053] In one embodiment, in existing dual heterojunction type mercury sulfide colloidal quantum dot short-to-mid-infrared detectors, the top electrode is mostly an opaque metal electrode, while the bottom is an infrared-transmitting substrate. This bottom-transmitting mode limits its direct application in silicon-based readout circuits. Alternatively, ultrathin gold combined with ITO can be used as the top electrode to achieve top transparency, but this comes at the cost of sacrificing approximately 30-40% of incident light, reducing photoresponsivity and affecting detector performance. While direct deposition of transparent ITO electrodes can achieve top light transmission, the high-energy particles during magnetron sputtering deposition cause significant damage to the mercury sulfide quantum dot layer. Direct sputtering of ITO without any buffer layer protection introduces interface defects, increases dark current, and reduces detector performance. The infrared detection device provided in this application uses a magnetron sputtering process to fabricate an ITO transparent electrode 60. While ensuring light transmission, a P-type thin film layer is set to protect the mercury sulfide quantum dot layer 40, thus buffering the mercury sulfide quantum dot layer 40. This prevents high-energy particles from damaging the mercury sulfide quantum dot layer 40 during the magnetron sputtering fabrication of the top electrode 60, thereby reducing interface defects in the infrared detector and lowering dark current.

[0054] Furthermore, in the scheme of this application, the material of the P-type thin film layer 50 includes ZnTe.

[0055] The bottom electrode 20 includes any one or more of Au and indium tin oxide (ITO).

[0056] The N-type thin film layer 30 includes any one of ZnO and SnO2. The thickness of the N-type thin film layer 30 is 20-200 nm. Specifically, if the N-type thin film layer 30 is a ZnO thin film, a thickness of 100 nm is optimal; if the N-type thin film layer 30 is a SnO2 thin film, a thickness of 30 nm is optimal.

[0057] The mercury sulfide quantum dot layer 40 includes any one of the following: weak p-type mercury sulfide quantum dots, intrinsic i-type mercury sulfide quantum dots, and n-type mercury sulfide quantum dots. Specifically, HgTe quantum dots with an absorption cutoff wavelength of 1100 nm to 1500 nm are weak p-type mercury sulfide quantum dots, HgTe quantum dots with an absorption cutoff wavelength of 1500 nm to 2500 nm are intrinsic i-type mercury sulfide quantum dots, HgTe quantum dots with an absorption cutoff wavelength of 2500 nm to 4000 nm are n-type mercury sulfide quantum dots, and HgSe and HgS quantum dots are n-type mercury sulfide quantum dots. More specifically, the mercury sulfide quantum dot layer 40 includes any one of the following: HgSe quantum dots, HgS quantum dots, and HgTe quantum dots with an absorption cutoff wavelength of 1100 nm to 4000 nm.

[0058] In one embodiment, the thickness of the mercury sulfide quantum dot layer 40 is greater than that of the N-type thin film layer 30 and the P-type thin film layer 50. Specifically, the thickness of the P-type thin film layer 50 is 10–100 nm, preferably 30 nm; the thickness of the N-type thin film layer 30 is 20–200 nm; and the thickness of the mercury sulfide quantum dot layer 40 is 200–500 nm, with 400 nm being optimal.

[0059] The top electrode 60 includes an ITO transparent electrode. The thickness of the top electrode 60 is 50–200 nm, preferably 100 nm.

[0060] The top electrode is fabricated using magnetron sputtering to create an ITO transparent electrode. While ensuring light transmission, a P-type thin film layer is set to protect the mercury sulfide quantum dot layer and buffer it. This prevents high-energy particles from damaging the mercury sulfide quantum dot layer during magnetron sputtering fabrication of the top electrode, thereby reducing interface defects in the infrared detector and lowering dark current.

[0061] Specifically, through experiments and implementation of the embodiments of the present invention, the following beneficial effects are observed:

[0062] (1) In this embodiment of the invention, a p-on-n type double heterojunction is formed by constructing an N-type thin film layer, a mercury thiosulfate quantum dot layer, and a P-type thin film layer. Compared with existing p-on-n type detectors, the device detectivity in the short-wave infrared band is 3.8*10. 11Jones, with an external quantum efficiency of 43.2%, offers superior performance. It has good applications in the detection of short waves in the 1100–2500 nm range and / or medium waves in the 3000–5000 nm range.

[0063] (2) The mercury thiosulfate quantum dot layer in this embodiment of the invention is prepared by liquid-phase exchange, which allows for one-step spin coating to obtain a quantum dot film of the desired thickness. The prepared quantum dot film is of high quality, has a uniform surface, and the preparation method is simple and controllable.

[0064] (3) In this embodiment of the invention, a P-type thin film layer is introduced on the mercury sulfide quantum dot layer. The ZnTe thin film can serve as both a buffer layer to prevent high-energy particles from damaging the mercury sulfide quantum dot layer and a hole transport layer to reduce interface defects and lower dark current. Furthermore, its high infrared transmittance helps the quantum dot layer absorb infrared light, thereby improving the device's responsivity.

[0065] (4) In this embodiment of the invention, by designing the top electrode as an ITO transparent electrode, it is beneficial to achieve integration with the focal plane array of the top incident mode.

[0066] The infrared detector designed in this invention has good applications in the short-wavelength detection range of 1100–2500 nm and / or the mid-wavelength detection range of 3000–5000 nm. Specifically, in the short-wavelength infrared field, it can image through glass, thus it can be applied to automotive night vision systems to enhance nighttime detection capabilities. Furthermore, the infrared detector of this application can also penetrate visible light-opaque materials such as plastics and silicon wafers, thus it can be applied to non-destructive testing and identification of materials. In the mid-wavelength infrared field, it can be applied in medical and health fields, security and inspection, etc.

[0067] Please see Figure 3 , Figure 3 This is a flowchart illustrating an embodiment of the method for fabricating an infrared detector according to this application, specifically including:

[0068] Step S31: Prepare an N-type thin film layer.

[0069] In one embodiment, the fabrication method further includes: providing a substrate and fabricating a bottom electrode on the substrate. Specifically, the substrate includes any one of glass, silicon wafer, quartz wafer, sapphire wafer, or flexible substrate. Taking a glass substrate as an example, the dimensions are length × width × thickness = 25mm × 25mm × 1mm. A 150nm thick ITO thin film is magnetron sputtered on the glass substrate as the bottom electrode. The bottom electrode is a circular electrode with a diameter of 2mm.

[0070] The N-type thin film layer is prepared by depositing ZnO or SnO2 on the side of the bottom electrode away from the substrate. The thickness of the N-type thin film layer is 20-200 nm; the N-type thin film layer includes any one of ZnO and SnO2. In a specific embodiment, if the N-type thin film layer is a ZnO thin film, a thickness of 100 nm is optimal; if the N-type thin film layer is a SnO2 thin film, a thickness of 30 nm is optimal. Taking ZnO as an example, a ZnO target with a purity greater than 99.99% is used, and a 100 nm ZnO thin film is deposited on the bottom electrode by magnetron sputtering to obtain the N-type thin film layer.

[0071] Step S32: Prepare a mercury thiosulfate quantum dot layer on the N-type thin film layer.

[0072] In one embodiment, a quantum dot solution is first prepared. The quantum dot solution includes any one of HgSe quantum dots, HgS quantum dots, and HgTe quantum dots with an absorption cutoff wavelength of 1100 nm to 4000 nm. The preparation of the quantum dot solution includes: adding a tellurium precursor to a solution of mercuric chloride oleylamine containing long-chain ligands to synthesize an HgTe quantum dot solution. During this process, the synthesis temperature can be adjusted to change the absorption cutoff wavelength of the quantum dots; or, injecting selenourea dissolved in oleylamine into a long-chain ligand solution of mercuric chloride oleylamine to synthesize an n-type HgSe quantum dot solution; or, injecting a sulfur source dissolved in oleylamine into a long-chain ligand solution of mercuric chloride oleylamine to synthesize an n-type HgS quantum dot solution.

[0073] The quantum dot solution was subjected to liquid-phase ligand exchange using a mixture of HgCl2, mercaptoethanol, and n-butylamine in N,N-dimethylformamide solution; the solution after liquid-phase ligand exchange was precipitated with ethanol, and the precipitate was then prepared into a high-concentration coating solution of N,N-dimethylformamide and n-butylamine; a mercury thiosulfate quantum dot layer was prepared on the N-type thin film layer using the coating solution.

[0074] The following explanation uses HgTe quantum dot solution as an example:

[0075] Specifically, tellurium powder (Te) and trioctylphosphine (TOP) were heated and stirred to form a clear yellow tellurium precursor solution, TOPTE. A 1 mmol / mL TOPPTE solution was added to an oleylamine solution containing 0.9 mmol HgCl2 using a hot-injection method. The molar ratio of Te to HgCl2 was approximately 2:1. The temperature of the mixed solution was controlled at 50℃–90℃ to obtain a HgTe quantum dot solution with an absorption cutoff wavelength of 1100 nm–4000 nm. After washing once with ethanol, the solution was then dispersed in an octane solution for later use.

[0076] The HgTe quantum dot solution is subjected to liquid-phase ligand exchange using an N,N-dimethylformamide solution containing HgCl2, mercaptoethanol, and n-butylamine. The molar mass ratio of HgCl2, mercaptoethanol, and n-butylamine in the N,N-dimethylformamide solution is 1:2:4. The molar solubility of HgCl2 is 10 mM to 200 mM (1 mM = 1 mmol / L), preferably 50 mM. The molar solubility of mercaptoethanol is 10 mM to 400 mM, preferably 100 mM. The molar solubility of n-butylamine is 10 mM to 400 mM, preferably 200 mM. The solution after liquid-phase ligand exchange is precipitated with ethanol, and the precipitate is then prepared into a high-concentration coating solution of N,N-dimethylformamide and n-butylamine, wherein the volume ratio of the N,N-dimethylformamide and n-butylamine mixture is 3:7. A mercury sulfide quantum dot layer is prepared on the N-type thin film layer using a coating solution; specifically, a spin-coating method is employed. During spin-coating, the spin-coating speed is 1000–4000 rpm, the spin-coating acceleration is 100–1000 radians per square second, and the spin-coating time is 20–60 seconds per coat. Preferably, the spin-coating speed is 2000 rpm, the spin-coating acceleration is 500 radians per square second, and the spin-coating time is 40 seconds per coat. The thickness of the mercury sulfide quantum dot layer is 200–500 nm, preferably 400 nm.

[0077] Step S33: Prepare a P-type thin film layer on the mercury thiosulfate quantum dot layer.

[0078] The N-type thin film layer, the mercury thiosulfate quantum dot layer, and the P-type thin film layer are used to form a p-on-n type double heterojunction.

[0079] ZnTe is deposited on the mercury sulfide quantum dot layer using thermal evaporation deposition to form the P-type thin film layer. In one embodiment, a certain amount, such as 100 mg, of ZnTe powder with a purity greater than 99.9% is taken, and a ZnTe thin film is deposited on the mercury sulfide quantum dot layer using thermal evaporation deposition. The ZnTe thin film thickness is 10–100 nm, preferably 30 nm in this invention.

[0080] In this embodiment, the thickness of the mercury thiosulfate quantum dot layer is greater than the thickness of the N-type thin film layer and the P-type thin film layer.

[0081] Step S34: A top electrode is fabricated on the side of the P-type thin film layer away from the N-type thin film layer using a magnetron sputtering process.

[0082] A 100 nm ITO electrode is deposited on the ZnTe thin film layer using magnetron sputtering to obtain a transparent top electrode. The thickness of the top electrode is 50–200 nm, preferably 100 nm.

[0083] The infrared detection device to be prepared uses an ITO transparent electrode fabricated by magnetron sputtering as the top electrode. While ensuring light transmission, a P-type thin film layer is set to protect the mercury sulfide quantum dot layer and buffer it. This prevents high-energy particles from damaging the mercury sulfide quantum dot layer during the magnetron sputtering fabrication of the top electrode, thereby reducing interface defects in the infrared detector and lowering dark current.

[0084] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. An infrared detector, characterized in that, Includes: N-type thin film layer, mercury thiosulfate quantum dot layer, P-type thin film layer, and top electrode; The mercury sulfide quantum dot layer is disposed between the N-type thin film layer and the P-type thin film layer, and the N-type thin film layer, the mercury sulfide quantum dot layer and the P-type thin film layer are used to form a p-on-n type double heterojunction; The top electrode is disposed on the side of the p-on-n type double heterojunction near the p-type thin film layer. The top electrode is prepared by magnetron sputtering. During the preparation of the top electrode, the p-type thin film layer is used to protect the mercury thiosulfate quantum dot layer.

2. The infrared detector according to claim 1, characterized in that, Also includes: Substrate; The bottom electrode is disposed on the substrate. The p-on-n type double heterojunction is disposed between the bottom electrode and the top electrode, and the bottom electrode and the top electrode are used to connect negative and positive charges to enable current conduction.

3. The infrared detector according to claim 1, characterized in that, The N-type thin film layer includes any one of ZnO and SnO2; The mercury sulfide quantum dot layer includes any one of HgSe quantum dots, HgS quantum dots, and HgTe quantum dots with an absorption cutoff wavelength of 1100 nm to 4000 nm. The P-type thin film layer includes ZnTe.

4. The infrared detector according to claim 2, characterized in that, The bottom electrode includes any one or more of Au and indium tin oxide (ITO); The top electrode is an ITO transparent electrode.

5. The infrared detector according to claim 3, characterized in that, The thickness of the mercury sulfide quantum dot layer is greater than that of the N-type and P-type thin film layers.

6. A method for fabricating an infrared detector, characterized in that, The method includes: Preparation of N-type thin film layers: A mercury thiogroup quantum dot layer was prepared on the N-type thin film layer; A P-type thin film layer is prepared on the mercury sulfide quantum dot layer; the N-type thin film layer, the mercury sulfide quantum dot layer, and the P-type thin film layer are used to form a p-on-n type double heterojunction. A top electrode is fabricated on the side of the P-type thin film layer away from the N-type thin film layer using a magnetron sputtering process.

7. The preparation method according to claim 6, characterized in that, The method further includes: Provide substrate; Fabricate the bottom electrode on the substrate; The steps for preparing the N-type thin film layer include: The N-type thin film layer is prepared by depositing ZnO or SnO2 on the side of the bottom electrode away from the substrate; The preparation of a P-type thin film layer on the mercury sulfide quantum dot layer includes: A ZnTe thin film was deposited on the mercury thiocyanate quantum dot layer.

8. The preparation method according to claim 6, characterized in that, The step of preparing a mercury thiosulfate quantum dot layer on the N-type thin film layer includes: Preparation of quantum dot solutions; Liquid-phase ligand exchange was performed on the quantum dot solution using a mixture of HgCl2, mercaptoethanol, and n-butylamine in N,N-dimethylformamide. The solution after liquid phase ligand exchange was precipitated with ethanol, and the precipitate was then prepared into a high-concentration coating solution of N,N-dimethylformamide and n-butylamine. A mercury thiogroup quantum dot layer was prepared on the N-type thin film layer using a coating solution; The preparation of the quantum dot solution includes: HgTe quantum dot solution was synthesized by adding the tellurium precursor to a solution of mercuric chloride oleylamine containing long-chain ligands; or n-type HgSe quantum dot solution was synthesized by injecting selenourea dissolved in oleylamine into a long-chain ligand solution of mercuric chloride oleylamine; or n-type HgS quantum dot solutions were synthesized by injecting a sulfur source dissolved in oleylamine into a long-chain ligand solution of mercuric oleylamine chloride.

9. The preparation method according to claim 7, characterized in that, The thickness of the mercury sulfide quantum dot layer is greater than that of the N-type and P-type thin film layers.

10. The preparation method according to claim 7, characterized in that, The thickness of the N-type thin film layer is 20–200 nm; the thickness of the mercury thiosulfate quantum dot layer is 200–500 nm; and the thickness of the P-type thin film layer is 10–100 nm.

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