Abstract

Electrical conductance measured from across or parallel to a {110} symmetrical grain boundary in SrTiO<inf>3</inf> is considerably lower than the ones of the adjoined (100) grains and a SrTiO<inf>3</inf> (100) single crystal, but these differences are decreased significantly upon UV irradiation. Based on ultraviolet photoelectron spectroscopy and complementary conductive atomic force microscopy, we demonstrate that the hundredfold increases in the electrical conductance measured at the grain boundary are strongly associated with the ultraviolet-induced oxygen vacancies. Our results reveal the possibility of tuning the oxygen vacancies and electrical conductance at the grain boundary simply by UV irradiation, offering novel strategies for optoelectronic applications.