Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
Nanotechnology. 2019 May 17;30(20):205201. doi: 10.1088/1361-6528/ab0450. Epub 2019 Feb 4.
Amorphous aluminum oxide AlO (a-AlO) layers grown by various deposition techniques contain a significant density of negative charges. In spite of several experimental and theoretical studies, the origin of these charges still remains unclear. We report the results of extensive density functional theory calculations of native defects-O and Al vacancies and interstitials, as well as H interstitial centers-in different charge states in both crystalline α-AlO and in a-AlO. The results demonstrate that both the charging process and the energy distribution of traps responsible for negative charging of a-AlO films (Zahid et al 2010 IEEE Trans. Electron Devices 57 2907) can be understood assuming that the negatively charged O and V defects are nearly compensated by the positively charged H, V and Al defects in as prepared samples. Following electron injection, the states of Al, V or H in the band gap become occupied by electrons and sample becomes negatively charged. The optical excitation energies from these states into the oxide conduction band agree with the results of exhaustive photo-depopulation spectroscopy measurements (Zahid et al 2010 IEEE Trans. Electron Devices 57 2907). This new understanding of the origin of negative charging of a-AlO films is important for further development of nanoelectronic devices and solar cells.
通过各种沉积技术生长的非晶态氧化铝 AlO(a-AlO) 层含有大量的负电荷。尽管进行了多项实验和理论研究，但这些电荷的起源仍不清楚。我们报告了在不同电荷态下，晶体α-AlO 和非晶态 a-AlO 中本征缺陷-O 和 Al 空位和间隙以及 H 间隙中心的密度泛函理论计算的结果。结果表明，假设在制备样品中，带负电的 O 和 V 缺陷几乎被带正电的 H、V 和 Al 缺陷所补偿，那么 a-AlO 薄膜的负电荷形成过程和导致负电荷的陷阱的能量分布都可以用这一模型来理解。电子注入后，带隙中 Al、V 或 H 的状态被电子占据，样品带负电。这些状态到氧化物导带的光学激发能与详尽的光排空光谱测量结果（Zahid 等人，2010 年 IEEE 电子器件汇刊，第 57 卷，第 2907 页）一致。这种对 a-AlO 薄膜负电荷形成的起源的新认识对于进一步开发纳米电子器件和太阳能电池非常重要。
