Improvement of electron mobility in La:BaSnO₃ thin films by insertion of an atomically flat insulating (Sr,Ba)SnO₃ buffer layer

One perovskite oxide, ASnO₃ (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO₃ substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO₃ / (Sr,Ba)SnO₃ for buffering this large lattice mismatch between La:BaSnO₃ and SrTiO₃ substrate. The insertion of 200-nm-thick BaSnO₃ on (Sr,Ba)SnO₃ bilayer buffer structures reduces the number of dislocations and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO₃ buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO₃ shows that the highest obtained value of mobility is 78 cm²V⁻¹s⁻¹ because of its fewer dislocations. High electron mobility films based on perovskite BaSnO₃ can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.