Epitaxial La-doped BaSnO₃ films were grown in an adsorption-controlled regime by molecular-beam epitaxy, where the excess volatile SnO_x desorbs from the film surface. A film grown on a (001) DyScO₃ substrate exhibited a mobility of 183 cm² V⁻¹ s⁻¹ at room temperature and 400 cm² V⁻¹ s⁻¹ at 10 K despite the high concentration (1.2 × 10¹¹ cm⁻²) of threading dislocations present. In comparison to other reports, we observe a much lower concentration of (BaO)₂ Ruddlesden-Popper crystallographic shear faults. This suggests that in addition to threading dislocations, other defects—possibly (BaO)₂ crystallographic shear defects or point defects—significantly reduce the electron mobility.

Thermoelectric effects, measured by the Seebeck coefficients, refer to the phenomena in which a temperature difference or gradient imposed across a thermoelectric material induces an electrical potential difference or gradient, and vice versa, enabling the direct conversion of thermal and electric energies. All existing first-principles calculations of Seebeck coefficients have been based on the Boltzmann kinetic transport theory. In this work, we present a fundamentally different method for the first-principles calculations of Seebeck coefficients without using any assumptions of the electron-scattering mechanism, being in contrast to the traditional theory by Cutler and Mott that shows the dependence of the Seebeck coefficient on the scattering mechanisms. It is shown that the Seebeck coefficient is a well-defined thermodynamic quantity that can be determined from the change in the chemical potential of electrons induced by the temperature change and thus can be computed solely based on the electronic density of states through first-principles calculations at different temperatures. The proposed approach is demonstrated using the prototype PbTe and SnSe thermoelectric materials.