Contribution of Surface Defects to the Interface Conductivity of SrTiO3/LaAlO3

• Published in: 中国物理快报：英文版 no. 8; pp. 105 - 108
• Main Author: 关丽 谈凤雪 贾国奇 申光明 刘保亭 李旭
• Format: Journal Article
• Language: English
• Published: 01.08.2016
• Subjects: 异质界面; 氧空位; 电导率; 第一性原理; 结构稳定性; 表面缺陷; 计算结果; 金属绝缘体转变
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/33/8/087301

Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO3/SrTiO3 interfaces are investigated. The results show that O vacancies at p-type interfaces have much lower formation energies, and Sr or Ti vacancies at n-type interfaces are more stable than the ones at p-type interfaces under O-rich conditions. The calculated densities of states indicate that O vacancies act as donors and give a significant compensation to hole carriers, resulting in insulating behavior at p-type interfaces. In contrast, Sr or Ti vacancies tend to trap electrons and behave as acceptors. Sr vacancies are the most stable defects at high oxygen partial pressures, and the Sr vacancies rather than Ti vacancies are responsible for the insulator-metal transition of n-type interface. The calculated results can be helpful to understand the tuned electronic properties of LaAlO3 /SrTiO3 heterointerfaces.