Elucidating the origins of the two-dimensional electron gas in LaVO3/SrTiO3 interfaces

The influence of growth rate and substrate temperature on the two-dimensional electron gas (2DEG) of LaVO3/SrTiO3 interfaces has been investigated. It is found that both growth rate and substrate temperature can modulate the structural and electrical properties of the LaVO3/SrTiO3 interfaces through oxygen substrate-to-film transfer. When the LaVO3 thin films are deposited at a low substrate temperature and a high growth rate, the LaVO3/SrTiO3 interfaces exhibit weak oxygen substrate-to-film transfer and resultant low density of oxygen vacancies in the SrTiO3 substrate. As a result, the intrinsic effect (polar discontinuity and/or dielectric screening) dominates the interfacial conduction, while the oxygen vacancies play a minor role. In contrast, the oxygen substrate-to-film transfer (oxygen vacancies in the SrTiO3 substrate) can be enhanced (increased) by depositing the LaVO3 thin films at lower growth rates and/or higher substrate temperatures. In this case, the contribution of oxygen vacancies to the interfacial conduction would prevail over the intrinsic effect. Our results elucidate the origins of 2DEG in the LaVO3/SrTiO3 interfaces and may also be important for other SrTiO3-based heterointerfaces.