Zhang Meng, Du Kai, Ren Tianshuang, Tian He, Zhang Ze, Hwang Harold Y, Xie Yanwu
Interdisciplinary Center of Quantum Information, Zhejiang Province Key Laboratory of Quantum Technology and Device, and Department of Physics, Zhejiang University, 310027, Hangzhou, China.
Center of Electron Microscopy, State Key Laboratory of Silicon Materials, and School of Materials Science and Engineering, Zhejiang University, 310027, Hangzhou, China.
Nat Commun. 2019 Sep 6;10(1):4026. doi: 10.1038/s41467-019-12036-5.
The single-crystal SrTiO (001) has two different surface terminations, TiO and SrO. One most remarkable observation in previous studies is that only the heterointerfaces with TiO-terminated SrTiO, which usually combines with polar oxides such as LaAlO, host an electron gas. Here we show that a robust electron gas can be generated between a non-polar oxide, CaHfO, and SrTiO (001) with either termination. Unlike the well-known electron gas of LaAlO/SrTiO, the present one of CaHfO/SrTiO essentially has no critical thickness of CaHfO, can survive a long-time oxygen annealing at high temperature, and its transport properties are stable under exposure to water and other polar solvents. By electrostatic gating through CaHfO, field-effect devices are demonstrated using CaHfO/SrTiO heterointerfaces with both terminations. These results show that the electron gas reported in the present study is unique and promising for applications in oxide electronics.
单晶SrTiO（001）有两种不同的表面终端，即TiO和SrO。以往研究中一个最显著的发现是，只有与TiO终端的SrTiO形成的异质界面（通常与极性氧化物如LaAlO结合）才会存在电子气。在此我们表明，在非极性氧化物CaHfO与任何一种终端的SrTiO（001）之间都能产生稳定的电子气。与众所周知的LaAlO/SrTiO电子气不同，目前的CaHfO/SrTiO电子气基本上不存在CaHfO的临界厚度，能在高温下长时间进行氧退火，并且其输运性质在暴露于水和其他极性溶剂时保持稳定。通过对CaHfO进行静电门控，展示了使用两种终端的CaHfO/SrTiO异质界面的场效应器件。这些结果表明，本研究中报道的电子气具有独特性，在氧化物电子学应用方面很有前景。
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