Structural, electronic, and optical absorption properties of orthorhombic CaSnO3 through ab initio calculations

Density functional theory ab initio calculations of the structural parameters, electronic structure, carriers' effective masses, and optical absorption of orthorhombic CaSnO3 were performed within the local density and generalized gradient approximations, LDA and GGA, respectively. A good agreement between the calculated lattice parameters and experimental results was obtained, and a direct energy gap of 1.95 eV (2.92 eV) is estimated in the GGA (LDA) for orthorhombic CaSnO3. The computed carriers' effective masses are small and practically isotropic for electrons, allowing us to suggest that direct gap orthorhombic CaSnO3 is a semiconductor with potential for optoelectronic applications. The optical absorption increases for photon energies larger than 7.0 eV due to the appearance of transitions involving O 2p valence states and Ca 3d conduction states