Fabrication and Characterization of (Ba,La)SnO3 Semiconducting Epitaxial Films on (111) and (001) SrTiO3 Substrates

Recently, BaSnO3 has attracted great attention as a promising transparent oxide semiconductor with a large bandgap (3.3 eV) and high mobility (320 cm(2) V-1 s(-1)), and many reports have discussed the origin of its high mobility. Specifically, its effective mass m* has been investigated with both calculations and experiments. First-principles calculations have suggested that m* is small near the Gamma point and that this m* assists the high mobility. Therefore, it is quite important to study the anisotropy in the mobility of this material. However, except for (001) BaSnO3, there are almost no reports on the electrical transport properties of the films with other orientations. In this paper, the authors fabricate (111) and (001) (Ba,La)SnO3 films by using pulsed laser deposition to evaluate the structural differences including the epitaxial strain and the orientation distribution generated from the differences in the growth mode that is originated in the ionic arrangement of each surface. The effects of the structural differences for the conductivities of (001) and (111) films and how do the authors achieve the epitaxial films with high mobility are discussed.