We show that N-polar GaN/AlGaN/GaN heterostructures exhibit significant N deficiency at the bottom AlGaN/GaN interface, and that these N vacancies are responsible for the trapping of holes observed in unoptimized N-polar GaN/AlGaN/GaN high electron mobility transistors. We arrive at this conclusion by performing positron annihilation experiments on GaN/AlGaN/GaN heterostructures of both N and Ga polarity, as well as state-of-the-art theoretical calculations of the positron states and positron-electron annihilation signals. We suggest that the occurrence of high interfacial N vacancy concentrations is a universal property of nitride semiconductor heterostructures at net negative polarization interfaces.

中文翻译：

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GaN /（Al，Ga）N / GaN异质结构中的界面N空位

我们显示N极性GaN / AlGaN / GaN异质结构在底部AlGaN / GaN界面处表现出明显的N缺乏，并且这些N空位是导致空穴在非优化N极性GaN / AlGaN / GaN高电子迁移率中捕获的原因晶体管。我们通过对N和Ga极性的GaN / AlGaN / GaN异质结构进行正电子experiments灭实验，以及对正电子态和正电子-电子signals灭信号的最新理论计算，得出了这一结论。我们认为，高界面氮空位浓度的出现是氮化物半导体异质结构在净负极化界面的普遍性质。