Oxygen diffusion process in a Ba 0.96 La 0.04 SnO 3 thin film on SrTiO 3 (001) substrate as investigated by time‐dependent Hall effect measurements

We investigate the oxygen diffusion phenomena in a Ba 0.96 La 0.04 SnO 3 (BLSO) thin film on SrTiO 3 (001) substrate by measurements of time‐dependent Hall effect at high temperatures around 500 °C under different gas atmosphere. Under the Ar (O 2 ) atmosphere, carrier density ( n ) and electrical conductivity ( σ ) are increased (decreased) while electron mobility ( µ ) is slightly reduced (enhanced). This observation supports that although both n and µ are affected by the oxygen diffusion process, the change of n is a major factor of determining σ in the BLSO film. Detailed analyses of the time‐dependent n exhibit fast and slow dynamics that possibly correspond to the oxygen exchange reaction at the surface and oxygen diffusion into the BLSO grains, respectively. Fitting the time dependence of n reveals that the chemical diffusion coefficient of oxygen in the BLSO grains becomes ∼10 −16  cm 2  s −1 . This coefficient marks the lowest value among perovskite oxides around 500 °C, directly proving excellent thermal stability of oxygen in BLSO. The present results support that the donor‐doped BaSnO 3 system could be useful for realizing transparent semiconductor devices at high temperatures.