The electronic band structure of CaSnN2 in the wurtzite-based Pna21 structure is calculated using the Quasiparticle Self-consistent (QS)GW$^{ BSE}$ method, including ladder diagrams in the screened Coulomb interaction W$^{ BSE}$ and is found to have a direct gap of 2.680 eV at { \Gamma}, which corresponds to blue light wavelength of 463 nm and makes it an attractive candidate for sustainable blue light-emitting diodes (LEDs), avoiding Ga and In. The valence band maximum has a1 symmetry and gives allowed transitions to the conduction band minimum for light polarized along the c-direction. The valence band splitting is analyzed in terms of symmetry labeling, and the effective mass tensor is calculated for several bands at { \Gamma}. The optical dielectric function, including electron-hole interaction effects is also reported, and the excitons are analyzed, including several dark excitons.
Categories: cond-mat.mtrl-sci cond-mat.other