NSF-BSF: Electrical mitigation of radiation-induced defects in InAs/GaSb structures for infrared sensing

红外（IR）光电探测器具有许多与安全相关的应用，从夜视和大规模火灾警报系统到拦截器导引头和早期导弹预警系统在宇宙中的IR传感。由于恐怖主义威胁是美国和其他国家日常现实的一部分，因此高效和辐射硬红外探测器阵列的可用性将有助于保护各国免受恐怖主义的侵害，从而挽救生命和财产。高能粒子对红外探测器的损伤会降低其在恶劣辐射环境中的灵敏度。该项目将导致基于InAs/GaSb结构的光电探测器的戏剧性恢复。这一结果将通过对材料的基本性质（电子扩散长度）进行电剪裁来实现，所述电剪裁通过在施加电压下的原位电荷注入来实现。光电探测器的灵敏度将完全恢复并恢复到辐照前的原始状态，甚至超过辐照前的水平。该项目将推进对InAs/GaSb基半导体和器件中点缺陷和扩展缺陷性质的基本理解。该项目将结合研究生和本科生的研究和教育，并与以色列特拉维夫大学的国际合作伙伴积极合作。该项目的重点是通过将电荷注入到基于InAs/GaSb超晶格的红外光电探测器中来减轻辐照引起的缺陷。最终目标是生产出抗辐射和高效的设备。该项目取决于PI先前的发现，即电荷注入InAs/GaSb II型应变层超晶格导致材料的电子特性发生相当大的变化，特别是载流子扩散长度。这些变化导致光电探测器量子效率的几倍增强。因此，它是可能的，以提高性能的光电探测器，辐射的影响，使用短脉冲的固态正向偏置电荷注入到InAs/GaSb的p-i-n器件。该项目将使人们更好地了解InAs和GaSb半导体与高能粒子（包括电子、伽马射线光子和质子）之间的相互作用，以及辐射引起的缺陷的性质。电荷注入将导致光电探测器的p型吸收层中的增强的少数电子扩散长度，从而增加器件的量子效率并“治愈”伽马射线、质子、电子和其他辐射类型的不利影响。PI实验室的电学和光学研究的独特组合将揭示机制，这是负责感兴趣的效果。利用电子束感生电流技术研究了不同温度下的少子扩散长度。深能级瞬态光谱学将允许辐射诱导的点缺陷的研究。光谱光响应测量将评估电荷注入对器件量子效率的影响。最终目标是关联电荷注入制度（电流;电压;持续时间）和辐照剂量，从而对光电探测器性能的控制和从辐射损伤的恢复进行纯电气手段。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Infrared (IR) photodetectors have many security-related applications ranging from night-vision and large-scale fire alarm systems to IR-sensing in the hither cosmos for interceptor seekers and early missile warning systems. As a threat of terrorism is a part of every-day reality for the US and other countries, availability of efficient and radiation hard IR detector arrays will help protecting countries from terrorism, thus saving lives and assets. Damage by energetic particles degrades the sensitivity of IR photodetectors in harsh radiation environments. This project will lead to a dramatic recovery of photodetectors based on InAs/GaSb structures. This outcome will be achieved by electrical tailoring of a fundamental property of the material, the electron diffusion length, by in-situ charge injection under applied voltage. Photodetector sensitivity will recover completely and return to the original state prior to irradiation or even exceed it. The project will advance the fundamental understanding of the nature of point and extended defects in InAs/GaSb-based semiconductors and devices. The project will integrate research and education at the graduate and undergraduate levels and features an active international partner from Tel Aviv University in Israel.This project focuses on electrical mitigation of irradiation-induced defects by charge injection into infrared photodetectors based on InAs/GaSb superlattices. The ultimate aim is to produce radiation hard and efficient devices. The project hinges on the PI's previous findings that charge injection into InAs/GaSb type-II strained-layer superlattices leads to considerable changes in the material's electronic properties, particularly the carrier diffusion length. These changes result in a several fold enhancements of the photodetector quantum efficiency. It is therefore possible to improve performance of photodetectors, affected by radiation, using short pulses of solid-state forward-bias charge injection into InAs/GaSb p-i-n devices. The project will lead to a better understanding of the interaction between InAs and GaSb semiconductors and highly energetic particles, including electrons, gamma-ray photons, and protons, as well as of the nature of radiation-induced defects. Charge injection will result in enhanced minority electron diffusion length in the p-type absorption layer of a photodetector, thus increasing the quantum efficiency for the device and "healing" the adverse impact of gamma-rays, protons, electrons, and other radiation types. A unique combination of electrical and optical studies in the PI’s lab will shed light on the mechanism, which is responsible for the effect of interest. Studies of minority carrier diffusion length will be conducted using electron beam-induced current technique at various temperatures. Deep level transient spectroscopy will allow studies of radiation-induced point defects. Spectral photoresponse measurements will assess the impact of charge injection on device quantum efficiency. The ultimate goal is to correlate charge injection regimes (current; voltage; duration) and irradiation doses, thus proceeding towards control of photodetector performance and recovery from radiation damage by purely electrical means.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.