Band alignment at epitaxial BaSnO3/SrTiO3(001) and BaSnO3/LaAlO3(001) heterojunctions

We have spectroscopically determined the band offsets at epitaxial interfaces of BaSnO3 with SrTiO3(001) and LaAlO3(001). The conduction band minimum is lower in electron energy in the BaSnO3 than in the SrTiO3 and LaAlO3 by 0.6 +/- 0.1 eV and 3.7 +/- 0.1 eV, respectively. Thus, electrons generated in the SrTiO3 and LaAlO3 and transferred to the BaSnO3 by modulation and polarization doping, respectively, are expected to drift under the influence of an electric field without undergoing impurity scattering and the associated loss of mobility. This result bodes well for the realization of oxide-based, high-mobility, two-dimensional electron systems that can operate at ambient temperature.