Ohmic contacts are formed by recess etching the source and the drain regions with line and dot patterns of a few hundred nanometers on an AlGaN/GaN heterostructure and treating the surface with tetramethylammonium hydroxide (TMAH) prior to ohmic metal deposition. Electrical characterizations show that ohmic behavior is obtained at a low annealing temperature of 700 ◦ C as the direct contact area to the two-dimensional electron gas (2DEG) is increased via the etched patterns, and the ohmic contact is further improved when the interface is treated with TMAH. The analyses based on transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microcopy confirm the presence of an improved ohmic contact interface and morphology, suggesting a novel and viable route towards the fabrication of AlGaN/GaN-based devices with improved controllability and reliability.

中文翻译：

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用于改进欧姆接触的 AlGaN/GaN 高电子迁移率晶体管上的凹槽蚀刻和四甲基氢氧化铵处理的纳米级图案

欧姆接触是通过在 AlGaN/GaN 异质结构上用几百纳米的线和点图案对源极和漏极区域进行凹槽蚀刻并在欧姆金属沉积之前用四甲基氢氧化铵 (TMAH) 处理表面来形成的。电学特性表明，在 700°C 的低退火温度下获得了欧姆行为，因为通过蚀刻图案增加了与二维电子气 (2DEG) 的直接接触面积，并且当界面为TMAH 处理。基于透射电子显微镜、扫描电子显微镜、能量色散 X 射线光谱和原子力显微镜的分析证实存在改进的欧姆接触界面和形态，