SGER: New Approach to Revolutionize a Photovoltaic Detector Performance Using Electron Injection-Induced Effects in AlGaN

宽禁带GaN基半导体由于其在现代电子学中的重要性而吸引了越来越多的关注。GaN的应用除了需要高质量材料的可用性之外，还需要对其基本电子特性进行可控的修改。 GaN基光伏探测器的光谱响应通常受到高能量下的大吸收系数和小的少数载流子扩散长度的限制。为了克服这些限制，最近的设计变化包括使用p-i-n而不是p-n结[1-4]，用AlxGa 1-xN [1-3]或半透明凹陷窗口[2]取代GaN，以及背照式检测器配置[3]。然而，调整基本的（Al）GaN属性，以提高III族氮化物器件的性能，从未被直接考虑过。该提案的创新之处在于通过调整（Al）GaN中的少数载流子扩散长度来显著增强光伏检测器的性能。扩散长度是决定探测器量子效率和光响应的重要参数。PI最近的发现[5-8]定义了基本概念，即通过在固态器件-p-n结或肖特基势垒中施加外部电压，将电子注入p-（Al）GaN中，增加了临界少数载流子扩散长度和寿命。在其他材料特性中观察到一致的变化，包括发光和光谱光响应，并归因于深亚稳Mg受体相关中心的充电[6]。 这项研究的现实意义是长远的（天），革命性的（达一个数量级！）（Al）GaN基光伏探测器的性能增强，通过短时间（至多1500秒）电子注入实现。这是因为增加的扩散长度改善了少数载流子收集并消除了“死区”，其中载流子在被收集之前重新组合。 拟议的项目具有高风险，因为必须确定p-（Al）GaN [5-8]中的新型电子注入诱导效应是否具有普遍性并代表p型材料的基本特性，或者它们是否取决于材料的质量，生长和加工条件。 如果这种效应确实具有普遍性，那么开发这种新颖而简单的方法将显示出很高的回报，通过操纵材料的传输特性来彻底改变光伏探测器的性能，这可能会与设计和技术改进相结合。SGER应用的成功将导致该方法在商业探测器中的实施，并将推动该技术在扩散长度至关重要的其他双极器件（晶体管，晶闸管）中的应用。 计划在此项目成功的基础上提交GOALI提案（与康宁合作）。这项研究的更广泛的影响将是对GaN和相关化合物中电子传输的深入了解，研究与教育的整合以及与工业的合作。

Wide band gap GaN-based semiconductors are attracting increasing attention due to their importance in modern electronics. The applications of GaN necessitate the controlled modification of its fundamental electronic properties, in addition to the availability of high quality material. The spectral response of the GaN-based photovoltaic detectors is generally limited by the large absorption coefficient at high energies and the small minority carrier diffusion length. Recent design changes, to overcome these limitations, include the use of p-i-n instead of p-n junction [1-4], substitution of GaN by AlxGa1-xN [1-3] or semitransparent recessed windows [2], and a back-illuminated detector configuration [3]. However, a tuning of fundamental (Al)GaN properties, to boost the performance of III-Nitride devices, was never directly considered. The innovation in this proposal is to significantly enhance a photovoltaic detector performance by tailoring the minority carrier diffusion length in (Al)GaN. The diffusion length is a crucial parameter for the detector quantum efficiency and photoresponse. The underlying concept is defined by the PI.s recent findings [5-8] that electron injection into p-(Al)GaN from the application of an external voltage in a solid state device--p-n junction or Schottky barrier-increases the critical minority carrier diffusion length and lifetime. Consistent changes were observed in other material properties, including luminescence and spectral photoresponse, and were attributed to charging of deep metastable Mg-acceptor-related centers [6]. The practical significance of this research is a long-term (days), revolutionary (up to an order of magnitude!) performance enhancement for (Al)GaN-based photovoltaic detectors, achieved through short time (at most 1500 sec) electron injection. This is because the increased diffusion length improves minority carrier collection and eliminates the "dead space", where carriers recombine before they are collected. The proposed project is of high risk, since it must be determined whether the novel electron injection-induced effects in p-(Al)GaN [5-8] are universal in nature and represent a fundamental property of the p-type material, or if instead they depend on the material's quality, growth, and processing conditions. If, indeed, the effects are universal, a high pay off will be manifested in a development of this novel and simple approach to revolutionize photovoltaic detector performance by manipulating the material.s transport properties, which will likely be used in combination with design and technology improvements. Success in this SGER application will lead to the implementation of this approach in commercial detectors, and will advance the frontiers of this technology for use in other bipolar devices for which the diffusion length is critical (transistors, thyristors) [6]. It is planned to submit a GOALI proposal (with Corning) based on success of this project. The broader impact of this research will be a dipper understanding of electron transport in GaN and related compounds, the integration of research with education, and partnership with industry.