Yan Xi, Wrobel Friederike, Tung I-Cheng, Zhou Hua, Hong Hawoong, Rodolakis Fanny, Bhattacharya Anand, McChesney Jessica L, Fong Dillon D
Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA.
Adv Mater. 2022 Jun;34(24):e2200866. doi: 10.1002/adma.202200866. Epub 2022 May 16.
Bulk SrTiO is a well-known band insulator and the most common substrate used in the field of complex oxide heterostructures. Its surface and interface with other oxides, however, have demonstrated a variety of remarkable behaviors distinct from those expected. In this work, using a suite of in situ techniques to monitor both the atomic and electronic structures of the SrTiO (001) surface prior to and during growth, the disappearance and re-appearance of a 2D electron gas (2DEG) is observed after the completion of each SrO and TiO monolayer, respectively. The 2DEG is identified with the TiO double layer present at the initial SrTiO surface, which gives rise to a surface potential and mobile electrons due to vacancies within the TiO adlayer. Much like the electronic reconstruction discovered in other systems, two atomic planes are required, here supplied by the double layer. The combined in situ scattering/spectroscopy findings resolve a number of longstanding issues associated with complex oxide interfaces, facilitating the employment of atomic-scale defect engineering in oxide electronics.
块状 SrTiO 是一种著名的带绝缘体，也是复杂氧化物异质结构领域中最常用的衬底。然而，其表面以及与其他氧化物的界面表现出了各种与预期不同的显著行为。在这项工作中，使用一套原位技术在生长之前和生长过程中监测 SrTiO(001) 表面的原子结构和电子结构，分别在每个 SrO 和 TiO 单层完成后观察到二维电子气 (2DEG) 的消失和重新出现。2DEG 与初始 SrTiO 表面存在的 TiO 双层有关，由于 TiO 吸附层内的空位，该双层会产生表面电势和移动电子。与在其他系统中发现的电子重构非常相似，这里需要两个原子平面，由双层提供。原位散射/光谱学的综合研究结果解决了一些与复杂氧化物界面相关的长期问题，促进了原子尺度缺陷工程在氧化物电子学中的应用。
