Xiang X, Qiao L, Xiao H Y, Gao F, Zu X T, Li S, Zhou W L
School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Sci Rep. 2014 Jun 27;4:5477. doi: 10.1038/srep05477.
Density functional theory calculations of NdAlO3/SrTiO3 heterostructure show that two-dimensional electron gas (2-DEG) is produced at the interface with a built-in potential of ~0.3 eV per unit cell. The effects of surface defects on the phase stability and electric field of 2-DEG have been investigated. It is found that oxygen vacancy is easily to form on the NdAlO3(001) surface, with a low threshold displacement energy and a low formation energy. This point defect results in surface reconstruction and the formation of a zigzag -Al-O-Al- chain, which quenches the built-in potential and enhances the carrier density significantly. These results will provide fundamental insights into understanding how surface defects influence the electronic behavior of 2-DEG and tuning their electronic properties through surface modification.
钕铝酸镧/钛酸锶异质结构的密度泛函理论计算表明，在界面处产生了二维电子气（2-DEG），每个晶胞的内建电势约为0.3电子伏特。研究了表面缺陷对2-DEG相稳定性和电场的影响。发现氧空位易于在钕铝酸镧（001）表面形成，其具有低的阈值位移能和低的形成能。这种点缺陷导致表面重构并形成锯齿状-Al-O-Al-链，这消除了内建电势并显著提高了载流子密度。这些结果将为理解表面缺陷如何影响2-DEG的电子行为以及通过表面改性调节其电子性质提供基本见解。
