GaN and related semiconductors have become an increasingly prominent material for a wide range of active and passive devices from optoelectronics to high frequency and power electronics as well as photocatalysis. Regardless of the application, anisotropic etching is required for micro and nano structuring, currently performed by reactive ion etching (RIE). Alternately, metal-assisted chemical etching (MacEtch) is an open-circuit plasma-free anisotropic etching method that has demonstrated high aspect ratio device structures devoid of plasma-induced damage found in RIE. This paper presents an in-depth study of the ensemble electrochemical mechanisms that govern the photo-enhanced MacEtch process of GaN and related heterojunctions. Through in-depth experimental investigations, modeling and simulations, the effects of local cathode and anode design, energy-band alignments, and solution chemistry on MacEtch are correlated with the underlying electronic mechanisms of carrier generation, annihilation, transport, and extraction, establishing a fundamental framework for parametrized prediction of system behavior. These findings carry profound implications for tailored design of photoelectrochemical processes employed not just for uniformly etching wide/ultrawide bandgap materials but more broadly for semiconductor-based photocatalytic reactions in general. One-pot photo-enhanced MacEtching of AlInGaN multi-heterojunction device structures including superlattices and multi-quantum wells are demonstrated.

中文翻译：

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揭秘 GaN 及相关异质结的金属辅助化学蚀刻

GaN 及相关半导体已成为从光电子到高频和电力电子以及光催化等各种有源和无源器件的日益重要的材料。无论何种应用，微米和纳米结构都需要各向异性蚀刻，目前通过反应离子蚀刻（RIE）进行。另外，金属辅助化学蚀刻 (MacEtch) 是一种开路无等离子体各向异性蚀刻方法，已证明高深宽比器件结构没有 RIE 中发现的等离子体引起的损坏。本文对控制 GaN 及相关异质结光增强 MacEtch 过程的整体电化学机制进行了深入研究。通过深入的实验研究、建模和模拟，局部阴极和阳极设计、能带排列和溶液化学对 MacEtch 的影响与载流子生成、湮灭、传输和提取的基本电子机制相关联，建立了系统行为参数化预测的基本框架。这些发现对于光电化学工艺的定制设计具有深远的影响，该工艺不仅适用于均匀蚀刻宽/超宽带隙材料，而且更广泛地适用于一般基于半导体的光催化反应。演示了包括超晶格和多量子阱在内的 AlInGaN 多异质结器件结构的一锅光增强 Mac 刻蚀。