Unraveling the Oxygen Effect on the Properties of Sputtered BaSnO₃ Thin Films

The perovskite oxide BaSnO3 is a highly topical material for next-generation transparent conducting semiconductors. The foreign chemical doping strategy is largely used to realize the high conductivity in BaSnO3. Removal of oxygen in BaSnO3 is another route to get high conductivity, but the oxygen vacancy–property relationships have not been realized completely, which is of fundamental importance for the future optoelectronic applications. Here we report how the oxygen vacancies in sputtered BaSnO3 films can account for the structural and chemical environment, the transport phenomena, and the optoelectronic properties. Oxygen vacancies in BaSnO3 films cause the expansion of the unit cell along the out-of-plane direction, enhance the conductivity, transform the electronic transport mechanism from the thermal activation model to the variable-range hopping (VRH) model, and spawn the sub-band level-assisted photoconduction. The present work further strengthens our understanding of the oxygen effect on the physical properties in BaSnO3-based systems.