Inflection points in the conduction-band structure of BaSnO3

BaSnO3 (BSO) is a wide-band-gap oxide in which very high levels of n-type doping have been demonstrated. Here we perform a detailed investigation of the conduction-band structure of BSO, reporting band velocities and effective masses as a function of energy, and explore whether sufficiently high doping levels can be achieved to fill the conduction band to energies near the inflection point. The presence of carriers near the inflection point can lead to negative differential resistance (NDR) due to the effective mass above the inflection point being negative. Our first-principles calculations, based on density functional theory with a hybrid functional, show that BSO has an inflection point 2.29 eV above the conduction-band minimum and that secondary conduction-band valleys are at least 2 eV higher in energy. We discuss the options available to achieve the required n-type doping levels to reach the inflection point in BSO.