Oxygen vacancies modulated photoelectrical properties in LaAlO3/SrTiO3 interface

We demonstrate the photoconductivity and related relaxation characteristics at the metallic interfaces between SrTiO3 (STO) substrates and LaAlO3 (LAO) films deposited at oxygen pressures ranged from 2 × 10−3 to 2 × 10−6 Torr. The photoconductivity results show that all the LAO/STO interfaces exhibit both persistent and transient photoconductivity, which decrease rapidly with increasing oxygen vacancies in the heterostructures. Using double exponential model, the photoinduced relaxation processes are also analyzed. The interface with less oxygen vacancies shows slower resistance recovery process. Our results provide deeper insight into the optoelectric response of two-dimensional electron gas at complex oxides interface.