HgCdTe double-layer component hetero-plane junction infrared detector and preparation method
The fabrication of a mercury cadmium telluride (MCH) bilayer heterojunction detector using mercury-rich vertical liquid phase epitaxy technology solves the problems of material damage and impurity diffusion in mesa heterojunction processes, achieving low dark current and long wavelength response, thus improving the performance of the MCH infrared detector.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KUNMING INST OF PHYSICS
- Filing Date
- 2024-10-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing mercury cadmium telluride infrared detectors suffer from difficulties in fabrication, severe material damage, poor passivation layer coverage, and poor interface in mesa heterojunction processes, leading to increased leakage current and dark current. Furthermore, the planar heterojunction process of MBE technology is difficult to control for impurities, and impurity diffusion is a serious problem.
A mercury-rich vertical liquid phase epitaxy technique was used to fabricate a mercury cadmium telluride bilayer heterojunction detector. Interfacial interdiffusion was achieved through the growth of an n-type wide bandgap heterolayer, and a P-on-n planar heterojunction was formed by As ion implantation. This avoided damage to the material during the mesa fabrication process. Furthermore, the heterojunction structure was formed through band modulation to suppress tunneling current and surface leakage current.
It effectively reduces dark current, improves device performance, achieves dark current level at Rule22 at low temperature, and reaches a response wavelength of 13.3 micrometers. It avoids material damage and impurity diffusion problems during mesa fabrication process and improves impurity control capability.
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Figure CN119342940B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of mercury cadmium telluride infrared detector technology, and particularly relates to a P-on-n type mercury cadmium telluride bilayer component heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology and its preparation method. Background Technology
[0002] Infrared focal plane array detectors have been widely used in military, industrial, environmental, and medical fields. Among numerous infrared detection materials, mercury cadmium telluride (HCDT) stands out for its high quantum efficiency. By changing the composition x, its bandgap can satisfy infrared detection within three atmospheric windows: 1–3 μm, 3–5 μm, and 8–14 μm, demonstrating significant advantages in fundamental physical properties. HCDT infrared focal plane array detectors have now reached their third generation, characterized by large array size, very long wavelengths, multicolor technology, and HOT (Hot Tone) devices, giving them a dominant position in high-end infrared detection.
[0003] The main technological routes for mercury cadmium telluride (HCd) infrared detectors include two structures: N-on-p and P-on-n. Currently, in mature device fabrication processes, the quantum efficiency of infrared detectors is above 80%, even reaching 100%. From the perspective of optical signal alone, the potential for significantly improving device performance is limited. In contrast, by reducing dark current, the performance of HCd infrared detectors can be improved by several orders of magnitude. Among the two structures, the P-on-n infrared detector has a significant advantage in reducing dark current, achieving a reduction of two orders of magnitude. The P-on-n technology route includes planar homojunctions (implanted junctions) and mesa heterojunctions (grown junctions).
[0004] The mesa heterojunction technology route utilizes in-situ As doping of HCC material, resulting in high activation efficiency. Indium-doped n-type HCC material is first grown on a substrate via liquid-phase epitaxy, followed by As-doped p-type HCC material. After appropriate activation annealing, a pn junction is formed. The n-type layer is the absorption layer, typically thicker than 5 μm, while the p-type layer is thinner, generally less than 2 μm. The p-type layer has a higher Cd content and a wider bandgap than the n-type layer, resulting in greater material stability and improved tunneling current and noise reduction. Its low-temperature performance is superior to that of homojunctions. In the mesa heterojunction process, mercury cadmium telluride (HCdT) array detectors need to isolate adjacent pixel pn junctions. Generally, etching / corrosion processes are used to isolate the p-type layer of each pixel. Damage to the HCdT material during mesa fabrication is unavoidable, and a large number of free sidewall surfaces are introduced into the process. Subsequent processes require fine passivation treatment of the surfaces. Compared with the planar junction process, the coverage and interface density of the sidewall passivation layer are worse than those of the planar junction, making passivation more difficult and the uniformity of mesa fabrication more difficult to control.
[0005] In the planar homojunction process, In-doped n-type mercury cadmium telluride (HCdT) is grown on a substrate via liquid-phase epitaxy. The p-region is then fabricated using As implantation. After As ion implantation, the HCdT requires high-temperature annealing to activate the HCdT before forming a pn junction. The planar homo-heterojunction process, however, cannot achieve surface bandgap modulation, has a high defect density in the implanted region, and requires complex annealing to reduce this density. This process is challenging, and residual defects can easily lead to increased dark current.
[0006] To circumvent the challenge of surface passivation in planar homojunction processes, a planar heterojunction process was developed. This process utilizes MBE (Metal-Based Enzyme Absorption) technology to fabricate a bilayer heterostructure with a high-resistivity surface. As ion implantation is then used to fabricate a P-on-n structure, and the device fabrication process is identical to that of the planar homojunction process. However, the planar heterojunction process based on MBE technology suffers from high dislocation density and significant challenges in impurity control. Furthermore, the subsequent annealing and activation process can easily lead to unintended impurity diffusion. Summary of the Invention
[0007] This invention provides a mercury cadmium telluride (MDT) bilayer heterojunction detector and its fabrication method, which solves the fabrication problem of MDT mesa heterojunction and further improves the performance of MDT planar junction detectors.
[0008] According to an embodiment of the present invention, a mercury cadmium telluride bilayer heterojunction detector includes a substrate material layer, an n-type absorption layer, an n-type wide bandgap heterojunction layer, a passivation layer, and a contact electrode layer stacked together.
[0009] The n-type wide bandgap heterolayer is a wide bandgap heterolayer prepared on the surface of an n-type absorber layer using mercury-rich vertical liquid phase epitaxy technology, and is a residual impurity n-type material;
[0010] The passivation layer covers at least a portion of the area of the isolation region and the p-type injection region in the orthographic projection direction, and the portion of the passivation layer not covering the p-type injection region is a contact hole;
[0011] The contact electrode layer is in contact with the p-type injection region, and the positive projection area of the contact electrode is larger than and covers the contact hole.
[0012] The mercury cadmium telluride (HCd) bilayer heterojunction detector based on mercury-rich vertical liquid phase epitaxy according to embodiments of the present invention utilizes the n-type wide bandgap heterolayer growth process to achieve interfacial interdiffusion, and realizes the HCd p-on-n planar heterojunction device through As ion implantation. Compared with ordinary mesa p-on-n heterojunction devices, it can effectively avoid the damage to the HCd material caused by the mesa fabrication process (dry etching or wet etching), and avoid leakage current caused by the mesa passivation layer coverage effect and poor interface. Compared with ordinary arsenic (As) implanted planar p-on-n homojunction devices, the heterojunction material structure formed by band modulation can effectively suppress tunneling current and surface leakage current, which is beneficial to reducing dark current and improving device performance. Compared with planar heterojunction devices based on MBE technology, it has high impurity control capability and good interfacial diffusion effect.
[0013] According to some embodiments of the present invention, both the n-type absorber layer and the n-type wide bandgap heterolayer are made of Hg. 1-x Cd x Te, where the value of x is less than or equal to 0.6.
[0014] According to some embodiments of the present invention, the n-type absorber layer is an In-doped material with an In doping concentration ranging from 1E¹⁴ cm⁻³ to 5E¹⁵ cm⁻³, Hg 1-x Cd x The x value in Te ranges from 0.1 to 0.4.
[0015] According to some embodiments of the present invention, the passivation layer thickness ranges from 500 angstroms to 20,000 angstroms, and the selected materials include, but are not limited to, CdTe, ZnS, SiN, and BN.
[0016] According to some embodiments of the present invention, the n-type wide bandgap heterolayer is produced using a mercury-rich vertical liquid phase epitaxy process, with residual impurities being n-type material and Hg. 1-x Cd x The x-values in Te range from 0.23 to 0.6, and are greater than the x-values in the absorption layer.
[0017] The present invention provides a mercury cadmium telluride bilayer heterojunction detector and its fabrication method based on mercury-rich vertical liquid phase epitaxy technology. This method is used to fabricate P-on-n type mercury cadmium telluride planar heterojunction detectors according to some embodiments of the present invention. The method includes:
[0018] An n-type absorption layer is grown on the substrate material layer;
[0019] A secondary growth is performed on the n-type absorber layer to prepare an n-type wide bandgap heterolayer;
[0020] Photolithography is performed on the surface of the n-type wide bandgap heterolayer. After development, an injection region and an isolation region protected by photoresist are formed, and the injection region is exposed.
[0021] As ions are used for ion implantation on the material surface. After implantation, the photoresist is removed and activated annealing is performed to form a P-region. Independent pixels are formed by separating them through n-type isolation regions.
[0022] A passivation layer is grown on the surface of an n-type wide bandgap heterolayer by magnetron sputtering, thermal evaporation, or MBE process.
[0023] Photolithography is performed on the surface of the passivation layer. After development, the contact hole area is exposed. The passivation layer is removed by etching or corrosion outside the photoresist protected area to prepare the contact hole.
[0024] The metal layer of the contact electrode is prepared using a thermal evaporation process;
[0025] The material is immersed in a stripping solution, and the photoresist and surface metal layer on the surface of the protected area material are removed by the stripping process to obtain a P-on-n type mercury cadmium telluride planar heterojunction detector.
[0026] According to embodiments of the present invention, the P-on-n type mercury cadmium telluride (HCd) planar heterojunction detector utilizes the n-type wide bandgap heterolayer growth process to achieve interfacial interdiffusion, and realizes the HCd p-on-n planar heterojunction device through As ion implantation. Compared with ordinary mesa p-on-n heterojunction devices, it can effectively avoid the damage to the HCd material caused by the mesa fabrication process (dry etching or wet etching), and avoid leakage current caused by the mesa passivation layer coverage effect and interface poorness. Compared with ordinary arsenic (As) implanted planar p-on-n homojunction devices, the heterojunction material structure formed by band modulation can effectively suppress tunneling current and surface leakage current, which is beneficial to reducing dark current and improving device performance. Compared with bilayer component heteromaterials prepared by MBE technology, the mercury-rich liquid-phase epitaxial HCd process can control the residual impurities to 8E13 / cm. 3 Horizontal, MBE technology can generally only control the level at E14 / cm. 3 The horizontal level provides stronger impurity control. According to some embodiments of the present invention, both the n-type absorber layer and the arrayed p-type cap region are made of Hg. 1-x Cd x Te, where the value of x is less than or equal to 0.6.
[0027] The beneficial effects of this invention are as follows:
[0028] Through experimental comparison, thanks to the natural passivation effect of the surface heterolayer and the band modulation structure, the dark current level of this structure device at low temperature reaches the Rule22 level (empirical formula for dark current of P-on-n device), and the longest response wavelength of the device reaches 13.3 micrometers (77K). Attached Figure Description
[0029] Figure 1 This is a schematic diagram of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology according to an embodiment of the present invention.
[0030] Figure 2 This is a top view of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology according to an embodiment of the present invention.
[0031] Figure 3 The diagram below shows the structure of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S100 of an embodiment of the present invention.
[0032] Figure 4 The diagram below shows the structure of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S200 of an embodiment of the present invention.
[0033] Figure 5 The diagram below shows a mercury cadmium telluride bilayer heterostructure planar junction detector structure based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S300 of an embodiment of the present invention.
[0034] Figure 6 This is a schematic diagram of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology, shown in step S400 of an embodiment of the present invention.
[0035] Figure 7 The diagram below shows a mercury cadmium telluride bilayer heterostructure planar junction detector structure based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S500 of an embodiment of the present invention.
[0036] Figure 8 The diagram below shows a mercury cadmium telluride bilayer heterostructure planar junction detector structure based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S600 of an embodiment of the present invention.
[0037] Figure 9 The diagram below shows a mercury cadmium telluride bilayer heterostructure planar junction detector structure based on mercury-rich vertical liquid phase epitaxy technology, as shown in step S700 of an embodiment of the present invention.
[0038] Figure 10 This is a flowchart illustrating the fabrication method of a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy according to an embodiment of the present invention.
[0039] Figure 11 This is a signal response diagram of the detector of the present invention.
[0040] Figure 12 This is a diagram showing the material composition and In impurity distribution.
[0041] The reference numerals in the figure are: 1-substrate material layer, 2-n-type absorber layer, 3-n-type wide bandgap heterostructure layer, 4-P-type implantation region, 5-passivation layer, 6-contact electrode layer, 7-photoresist, 8-metal layer. Detailed Implementation
[0042] To make the objectives, content, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The accompanying drawings form part of this application and are used to illustrate the principles of the present invention.
[0043] In related technologies, because mercury cadmium telluride (HCd) multi-element, area array detectors require isolation of adjacent pixel pn junctions, heterojunction HCd devices generally employ mesa fabrication to isolate the p-type layer of each pixel. However, compared to planar implanted junctions, mesa fabrication is more difficult, mainly because damage to the HCd material during mesa fabrication is unavoidable, and the passivation layer coverage on the mesa sidewalls is poorer than in planar fabrication, easily leading to surface leakage and device failure.
[0044] The present invention aims to solve the above-mentioned technical problems to a certain extent, and provides a mercury cadmium telluride bilayer heterostructure planar junction detector based on mercury-rich vertical liquid phase epitaxy technology and its preparation method.
[0045] like Figure 1 and Figure 2 As shown, the mercury cadmium telluride bilayer heterostructure detector based on mercury-rich vertical liquid phase epitaxy technology provided in this embodiment of the invention includes: a substrate material layer 1, an n-type absorption layer 2, an n-type wide bandgap heterostructure layer 3, a p-type implantation region 4, a passivation layer 5, and a contact electrode layer 6, which are stacked together.
[0046] After the n-type wide bandgap heterolayer 3 is grown, an array of p-type injection regions 4 is formed by photolithography. Independent pixels are then selectively injected into the n-type wide bandgap heterolayer. In actual device fabrication, detectors of different specifications and shapes can be formed by adjusting the shape and size of the photolithographic pattern. Here, only one example is used. Figure 2 The rectangular area shown is for illustrative purposes only.
[0047] like Figure 1 and Figure 2 As shown, the passivation layer 5 covers the pixel isolation area and part of the p-type injection area 4 in the orthogonal projection direction, and the uncovered part is the electrode contact hole.
[0048] The P-on-n type mercury cadmium telluride (HCd) planar heterojunction detector according to embodiments of the present invention utilizes the n-type wide bandgap heterolayer growth process to achieve interfacial interdiffusion, and realizes the HCd p-on-n planar heterojunction device through As ion implantation. Compared with ordinary mesa p-on-n heterojunction devices, it can effectively avoid damage to the HCd material caused by the mesa fabrication process (dry etching or wet etching), and avoid leakage current caused by the mesa passivation layer coverage effect and poor interface. Compared with ordinary arsenic (As) implanted planar p-on-n homojunction devices, the heterojunction material structure formed by bandgap modulation can effectively suppress tunneling current and surface leakage current, which is beneficial to reducing dark current and improving device performance. Compared with planar heterojunction devices based on MBE technology, it has higher impurity control capability and better interfacial diffusion effect.
[0049] like Figure 1 and Figure 2 As shown, according to some embodiments of the present invention, the materials of the n-type absorber layer 2 and the n-type wide bandgap heterolayer 3 are Hg. 1-x Cd x The values of Te and x are less than 0.6. By adjusting the components (x values), the response wavelength can be adjusted, thereby changing the detector's response wavelength according to different detection requirements.
[0050] like Figure 1 and Figure 2 As shown, according to some embodiments of the present invention, the n-type absorber layer 2 is an In-doped material with an In doping concentration ranging from 1E14cm-3 to 5E15cm-3, the x value in Hg1-xCdxTe is 0.1 to 0.4, and the x value of the n-type wide bandgap heterolayer 3 is higher than that of the n-type absorber layer 2.
[0051] like Figure 1 and Figure 2 As shown, according to some embodiments of the present invention, the thickness of the passivation layer 5 ranges from 500 angstroms to 20,000 angstroms, and the selected materials include, but are not limited to, CdTe, ZnS, SiN, BN, and combinations thereof.
[0052] The method for fabricating a mercury cadmium telluride bilayer heterojunction detector based on mercury-rich vertical liquid phase epitaxy technology provided in this invention embodiment is used to fabricate P-on-n type mercury cadmium telluride planar heterojunction detectors according to some embodiments of this invention. The method includes:
[0053] S100: As Figure 3 As shown, an n-type absorber layer 2 is grown on the substrate material layer 1.
[0054] S200: such as Figure 4 As shown, a secondary growth is performed on the n-type absorption layer 2 to grow an n-type wide bandgap heterolayer 3.
[0055] S300: such as Figure 5 As shown, photolithography is performed on the n-type wide bandgap heterolayer 3, and after development, the p-type implantation region 4 is exposed. After As ion implantation, activation annealing is performed.
[0056] S400: such as Figure 6 As shown, a passivation layer 5 is prepared on the material surface using magnetron sputtering, thermal evaporation, or MBE methods.
[0057] S500: such as Figure 7 As shown, photolithography is performed on the surface of passivation layer 5. In the area where the photoresist is exposed, etching / corrosion is used to remove the passivation layer and a small portion of the thin film material to prepare a contact hole, and then the photoresist is removed.
[0058] S600: such as Figure 8 As shown, photolithography is performed on the material surface, and after development, the area where the contact electrode layer 6 needs to be grown is exposed.
[0059] S700: such as Figure 9 As shown, the metal of electrode layer 8 is grown using a thermal evaporation process.
[0060] S800: The detector is immersed in a stripping solution. Through a stripping process, photoresist 7 and part of the metal layer on its surface are removed. The remaining metal forms electrode layer 6, thus obtaining… Figure 1 The image shows a mercury cadmium telluride planar heterojunction detector.
[0061] In some embodiments of the present invention, the n-type absorber layer 2 and the n-type wide bandgap heterolayer are grown by mercury-rich vertical liquid phase epitaxy (VLPE) without actively doping with other impurities during growth, and the remaining impurities are n-type.
[0062] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0063] First, such as Figure 3 As shown, using cadmium zinc telluride as the substrate material, an n-type absorber layer 2 is grown using LPE technology. The Hg content of the n-type absorber layer 2 is... 1-x Cd x The x-value of Te is 0.23, and the n-type concentration is 1×10⁻⁶. 14 cm -3 This step is an existing process; the structure of this patent is prepared based on this material, see [link / reference]. Figure 12 .
[0064] like Figure 4 As shown, a secondary growth process was performed on the n-type material using a mercury-rich vertical liquid phase epitaxy process to prepare an n-type wide bandgap heterolayer, with the n-type absorber layer 2 containing Hg. 1-x Cd xThe x-value of Te is 0.31, which is higher than that of the n-type absorption layer, see [reference needed]. Figure 12 .
[0065] like Figure 5 As shown, photolithography is performed on an n-type wide bandgap heterolayer. After development, the p-type implantation region is exposed. As ion implantation is then performed, followed by activation annealing.
[0066] like Figure 6 As shown, a CdTe+ZnS composite passivation layer 5 with a thickness of 5000 angstroms was prepared on the material surface by magnetron sputtering.
[0067] like Figure 7 As shown, photolithography is performed on the surface of the passivation layer. In the area where the photoresist is exposed, ICP etching / corrosion and other methods are used to remove the passivation layer and a small portion of the thin film material to prepare the contact hole, and then the photoresist is removed.
[0068] like Figure 8 As shown, photolithography is performed in the pixel area, and photoresist 7 covers the chip surface. After development, the area where the contact electrode layer 6 needs to be grown is exposed, and the photoresist thickness is greater than 3 micrometers.
[0069] like Figure 9 As shown, the metal of the contact electrode layer 6 is grown using a thermal evaporation process, such as a three-layer metal of Cr (1000 Å) + Pt (2000 Å) + Au (1000 Å).
[0070] Finally, the detector is immersed in a stripping solution, and the photoresist and the metal layer on the photoresist surface are removed through a stripping process to obtain... Figure 1 The detector structure is shown.
[0071] After coupling the detector to the silicon readout circuit using a mature flip-chip interconnect process, the detector is then packaged and tested to obtain... Figure 11 The detector response signal diagram is shown.
[0072] This invention effectively avoids the damage to the mercury cadmium telluride (MCH) material caused by the mesa fabrication process (dry etching or wet etching) in traditional mesa p-on-n heterojunction technologies based on MCH heterojunction materials. It utilizes the n-type wide bandgap heterolayer growth process to achieve interfacial interdiffusion, and realizes the MCH p-on-n planar heterojunction device through As ion implantation. Compared to ordinary mesa p-on-n heterojunction devices, it effectively avoids the damage to the MCH material caused by the mesa fabrication process (dry etching or wet etching), and avoids leakage current caused by the mesa passivation layer coverage effect and poor interface. Compared to ordinary arsenic (As) implanted planar p-on-n homojunction devices, the heterojunction material structure formed by bandgap modulation can effectively suppress tunneling current and surface leakage current, which is beneficial for reducing dark current. Compared to planar heterojunction processes based on MBE technology, it has better impurity control capabilities (e.g., Figure 12 As shown in the figure, the material has a low dislocation density, which helps to reduce dark current and improve device performance.
Claims
1. A mercury cadmium telluride bilayer heterojunction infrared detector, characterized in that, It includes a substrate material layer, an n-type absorption layer, an n-type wide bandgap heterolayer, a passivation layer, and a contact electrode layer stacked together; The n-type wide bandgap heterolayer is composed of n-type material with residual impurities. This n-type wide bandgap heterolayer is prepared on the surface of an n-type absorber layer using a mercury-rich vertical liquid phase epitaxy process, with residual impurities controlled at 8E13 / cm². 3 Within; the passivation layer covers at least a portion of the area of the isolation region and the p-type injection region in the orthographic projection direction, and the portion of the passivation layer not covering the p-type injection region is a contact hole; The contact electrode layer is in contact with the p-type injection region and the positive projection area of the contact electrode is larger than and covers the contact hole; After the n-type wide bandgap heterolayer is grown, an array of p-type injection regions is formed by photolithography. As impurities are selectively injected into the n-type wide bandgap heterolayer. After annealing and activation, independent pixels with a P-on-n structure are formed. The mercury cadmium telluride bilayer heterostructure planar junction is used to suppress tunneling current and surface leakage current, as well as reduce dark current.
2. The mercury cadmium telluride bilayer heterojunction infrared detector according to claim 1, characterized in that: The substrate layer is made of Cd. 1-x Zn x One of the Te or Si-based alternative substrates, wherein the x value is less than 0.
5.
3. The mercury cadmium telluride bilayer heterojunction infrared detector according to claim 1, characterized in that: Both the n-type absorber layer and the n-type wide bandgap heterolayer are made of Hg. 1-x Cd x Te, where the value of x is less than or equal to 0.
6.
4. The mercury cadmium telluride bilayer heterojunction infrared detector according to claim 3, characterized in that: The material of the n-type absorber layer is Hg. 1-x Cd x The x value in Te ranges from 0.1 to 0.
4.
5. The mercury cadmium telluride bilayer heterojunction infrared detector according to claim 3, characterized in that: The material Hg of the n-type wide bandgap heterolayer 1-x Cd x The x value in Te ranges from 0.23 to 0.
6.
6. The mercury cadmium telluride bilayer heterojunction infrared detector according to any one of claims 1-5, characterized in that: The passivation layer thickness ranges from 500 angstroms to 20,000 angstroms.
7. The mercury cadmium telluride bilayer heterojunction infrared detector according to any one of claims 1-5, characterized in that: The passivation layer material includes any one or a combination of several of the following materials: CdTe, ZnS, SiN, and BN.
8. A method for fabricating a mercury cadmium telluride bilayer heterojunction infrared detector as described in any one of claims 1-7, characterized in that, The method includes: An n-type absorption layer is grown on the substrate material layer; A secondary growth was performed on the n-type absorber layer using mercury-rich vertical liquid phase epitaxy to prepare an n-type wide bandgap heterolayer. Photolithography is performed on the surface of the n-type wide bandgap heterolayer. After development, an injection region and an isolation region protected by photoresist are formed, and the injection region is exposed. After photolithography, As ions are used for ion implantation. After implantation, the photoresist is removed and activated annealing is performed to form the P region. Independent pixels are formed by separating them through isolation regions. A passivation layer is grown on the surface of an n-type wide bandgap heterolayer by magnetron sputtering, thermal evaporation, or MBE process. Photolithography is performed on the surface of the passivation layer, and the passivation layer is removed by etching or corrosion outside the photoresist protected area to prepare contact holes and strip the photoresist. Photolithography is performed in the pixel area, and after development, the area except for the contact electrode is protected. The metal layer of the contact electrode is prepared using a thermal evaporation process; The material is immersed in a stripping solution, and the photoresist and surface metal layer on the surface of the protected area material are removed by the stripping process to obtain a mercury cadmium telluride bilayer heterostructure planar junction infrared detector.
9. The method for fabricating a mercury cadmium telluride bilayer heterojunction infrared detector according to claim 7, characterized in that: The dark current level of the mercury cadmium telluride bilayer heterostructure planar junction infrared detector at low temperatures reaches the empirical formula for dark current in Rule 22.
10. The method for fabricating a mercury cadmium telluride bilayer heterojunction infrared detector according to claim 9, characterized in that: The mercury cadmium telluride bilayer heterostructure infrared detector has a maximum response wavelength of 13.3 micrometers at 77K.