Electrical mitigation of radiation-induced defects in AlGaN/GaN photovoltaic detectors

非技术性：紫外光探测器有许多用途，如化学和生物分析或火焰检测。在恶劣的辐射环境中，含能粒子的损伤会降低紫外光探测器的灵敏度。该项目将大大提高基于氮化镓(GaN)的光电探测器的回收率。这一结果将通过在外加电压下原位电荷注入来对GaN的基本属性-电子扩散长度进行电学定制来实现。光电探测器的灵敏度将完全恢复，并恢复到照射前的原始状态。该项目将促进对GaN基半导体和器件中点缺陷和扩展缺陷的本质的基本理解。该项目将整合研究生和本科生层面的研究和教育，并以活跃的工业合作伙伴为特色。技术：该项目重点是通过向基于氮化镓(GaN)的紫外光探测器中注入电荷来电缓解辐射引起的缺陷。最终目标是生产抗辐射和高效的设备。这个项目是基于PI以前的发现，即电荷注入到p型GaN导致材料的电子性质，特别是载流子扩散长度发生了相当大的变化。这些变化导致光电探测器量子效率提高了一个数量级。因此，使用注入GaN p-i-n器件的固态正向偏置电荷的短脉冲来改善受辐射影响的光电探测器的性能是可能的。该项目将有助于更好地了解宽禁带半导体与高能粒子(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顶部p型吸收层中少数电子的扩散长度增加，从而提高器件的量子效率，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、光学和结构研究的独特组合将揭示导致兴趣效应的机制。少数载流子扩散长度和寿命的研究将在不同温度下使用电子束感应电流和超快时间分辨阴极发光的独立实验中进行。多色连续波阴极发光将被用来评估辐照对GaN中穿线位错密度的影响。最后，深能级瞬变光谱学将可以研究辐射引起的点缺陷。最终目标是将电荷注入制度(电流、电压、持续时间)和照射剂量联系起来，从而控制光电探测器的性能并通过纯电气方法从辐射损害中恢复。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical: Ultraviolet photodetectors have many uses, such as chemical and biological analysis or flame detection. Damage by energetic particles degrades the sensitivity of ultraviolet photodetectors in harsh radiation environments. This project will lead to a dramatic increase in the recovery of photodetectors based on gallium nitride (GaN). This outcome will be achieved by electrical tailoring of a fundamental property of GaN, 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. The project will advance the fundamental understanding of the nature of point and extended defects in GaN-based semiconductors and devices. The project will integrate research and education at the graduate and undergraduate levels and features an active industrial partner.Technical: This project focuses on electrical mitigation of irradiation-induced defects by charge injection into ultraviolet photodetectors based on gallium nitride (GaN). The ultimate aim is to produce radiation hard and efficient devices. This project hinges on the PI's previous findings that charge injection into p-type GaN leads to considerable changes in the material's electronic properties, particularly the carrier diffusion length. These changes result in an order of magnitude enhancement 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 GaN p-i-n devices. The project will lead to a better understanding of the interaction between wide gap 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 top 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, optical and structural 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 and lifetime will be carried out in independent experiments using electron beam-induced current and ultrafast time-resolved cathodoluminescence at various temperatures. Polychromatic continuous-wave cathodoluminescence will be employed for assessment of irradiation impact on threading dislocation density in GaN. Finally, deep level transient spectroscopy will allow studies of radiation-induced point defects. 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.