Structural and optoelectronic properties, and infrared spectrum of cubic BaSnO3 from first principles calculations

Abstract

The electronic band structure, density of states, dielectric function, optical absorption, and infrared spectrum of cubic BaSnO3 were simulated using density functional theory, within both the local density and generalized gradient approximations, LDA and GGA, respectively. Dielectric optical permittivities and polarizabilities at ω=0 and ω=∞ were also estimated. Indirect band gaps E(R→Γ) of 1.01 eV (LDA) and 0.74 eV (GGA) were found, which are smaller than the experimental one (≈3.1 eV). A comparison of the calculated cubic BaSnO3 band gap with those of others stannates ASnO3 (A = Ca, Sr, Cd) already published highlights their dependence on each crystal profile. The cubic BaSnO3 effective masses of electrons and holes were computed by parabolic fittings along different directions at the conduction band minimum and valence band maximum, being anisotropic for both electrons and holes. The experimental band gap and calculated effective masses confirm the semiconductor character of cubic BaSnO3. Finally, the vibrational normal modes and the infrared spectrum of cubic BaSnO3 were obtained and assigned.