We report a novel Sc/Al/Ni/Au metal scheme for Ohmic contacts to InAlN/GaN HEMT structures on silicon. A contact resistance of 0.39 Ω-mm with a low surface roughness of 20± 3 nm of the annealed contact has been achieved using this metal scheme. The microstructure of the region under the contacts revealed the formation of ~60 nm deep ScGaN inclusions in the GaN channel layer. A thin (~3-5 nm) non-uniform layer of ScInAlN is observed on top of InAlN barrier. Field-emission is found to be the dominant conduction mechanism. Polarization mismatch arising due to the structural modifications is used to explain the possible mechanism related to Ohmic contact formation.

中文翻译：

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硅上 InAlN/GaN 异质结构的钪基欧姆接触


我们报告了一种新颖的 Sc/Al/Ni/Au 金属方案，用于硅上 InAlN/GaN HEMT 结构的欧姆接触。使用这种金属方案，退火接触点的接触电阻为 0.39 Ω-mm，表面粗糙度为 20± 3 nm。接触下方区域的微观结构揭示了 GaN 沟道层中形成了约 60 nm 深的 ScGaN 夹杂物。在 InAlN 势垒顶部观察到一层薄（约 3-5 nm）的 ScInAlN 不均匀层。场发射被发现是主要的传导机制。由于结构修改而产生的极化失配用于解释与欧姆接触形成相关的可能机制。