Oxygen vacancies induced switchable and nonswitchable photovoltaic effects in Ag/Bi_(0.9)La_(0.1)FeO_3 /La_(0.7)Sr_(0.3)MnO_3 sandwiched capacitors

摘要

The short circuit photocurrent (I_(sc)) was found to be strongly dependent on the oxygen vacancies (V_(Os)) distribution in Ag/Bi_(0.9)La_(0.1)FeO_3 /La_(0.7)Sr_(0.3)MnO_3 heterostructures. In order to manipulate the Vo_s accumulated at either the Ag/Bi_(0.9)La_(0.1)FeO_3 or the Bi_(0.9)La_(0.1)FeO_3/La_(0.7)Sr_(0.3)MnO_3 interface by pulse voltages, switchable or nonswitchable photocurrent can be observed without or with changing the polarization direction. The sign of photocurrent could be independent of the direction of polarization when the variation of diffusion current and the modulation of the Schottky barrier at the Ag/Bi_(0.9)La_(0.1)FeO_3 interface induced by oxygen vacancies are large enough to offset those induced by polarization. Our work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities.