Key Takeaways & Executive Findings
- •• A planar junction MWIR photodetector based on InAs/GaSb T2SLs was fabricated using MBE growth and Zn thermal diffusion, achieving a 50% cut-off wavelength of 5.26 μm at 77 K. • The device exhibits a low dark current density of 8.67 × 10−5 A/cm2, a high quantum efficiency of 42.5%, and a peak detectivity of 3.90 × 1010 cm·Hz1/2/W at 77 K. • The effects of different Zn diffusion temperatures on dark current performance were systematically studied, optimizing the fabrication process. • A 640 × 512 focal plane array (FPA) was successfully fabricated, achieving a noise equivalent temperature difference (NETD) of 539 mK, demonstrating practical imaging capability.
Abstract
In this paper, a planar junction mid-wavelength infrared (MWIR) photodetector based on an InAs/GaSb type-Ⅱ superlattices (T2SLs) is reported. The Intrinsic-πMN superlattices was grown by the molecular beam epitaxy (MBE), followed with a ZnS layer grown by the chemical vapor deposition (CVD). The p-type contact layer was constructed by thermal diffusion in the undoped superlattices. The Zinc atom was successfully realised into the superlattice and a PπMN T2SL structure was constructed. Furthermore, the effects of different diffusion temperatures on the dark current performance of the devices were researched. The 50% cut-off wavelength of the photodetector is 5.26 μm at 77 K with 0 V bias. The minimum dark current density is 8.67 × 10−5 A/cm2 and the maximum quantum efficiency of 42.5%, and the maximum detectivity reaches 3.90 × 1010 cm·Hz1/2/W at 77 K. The 640 × 512 focal plane arrays (FPA) based on the planner junction were fabricated afterwards. The FPA achieves a noise equivalent temperature difference (NETD) of 539 mK.
1. Introduction
The mid-wavelength infrared (MWIR) photodetector operate in the wavelength range from 3 to 5 µm and hold significant promise in modern infrared devices due to the wide range of applications, such as industrial gas monitoring, environmental components analysis, and flame detection[1, 2]. Early studies of MWIR photodetectors primarily focused on HgCdTe and InSb materials. HgCdTe offers many advantages such as the tunable bandgap, high electron mobility, and the well-established industrial manufacturing foundation. However, the instability of its bulk, surface, and interface properties leads to poor uniformity and low production yield[3]. InSb exhibits excellent performance, high stability, and relatively low cost. However the response area is limited by the
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ZHANG Shihao, HAO Hongyue, ZHANG Ye, WANG Shuo, ZHANG Xiangyu, XIE Ruoyu, YAO Lingze, CHANG Faran, SHAN Yifan, LIU Haofeng, WANG Guowei, WU Donghai, JIANG Dongwei, XU Yingqiang, NIU Zhichuan, DONG Wenjing (2024). Mid-wavelength infrared planar junction photodetector based on InAs/GaSb Type-Ⅱ superlattices. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/24120014
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Frequently Asked Questions
What is the operating wavelength range of the photodetector?
The photodetector operates in the mid-wavelength infrared (MWIR) range, specifically from 3 to 5 μm, with a 50% cut-off wavelength of 5.26 μm at 77 K.
How was the p-type contact layer formed?
The p-type contact layer was formed by thermal diffusion of zinc atoms into the undoped InAs/GaSb type-II superlattice, creating a PπMN structure.
What are the key performance metrics at 77 K?
At 77 K, the photodetector exhibits a dark current density as low as 8.67 × 10−5 A/cm2, a maximum quantum efficiency of 42.5%, and a maximum detectivity of 3.90 × 1010 cm·Hz1/2/W.
What is the significance of the focal plane array (FPA) fabricated?
A 640 × 512 FPA was fabricated based on the planar junction, achieving a noise equivalent temperature difference (NETD) of 539 mK, demonstrating its potential for infrared imaging applications.
What growth techniques were used?
The InAs/GaSb type-II superlattice was grown by molecular beam epitaxy (MBE), and a ZnS layer was deposited by chemical vapor deposition (CVD).
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