Ab initiocalculation of the electronic structure and spectroscopic properties of spinelγ−Sn3N4

Abstract

The electronic structure and physical properties of $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Sn}}_{3}{\mathrm{N}}_{4}$ in the spinel structure are investigated by first-principles calculations. The calculated band structure, electronic bonding, and optical properties are compared with two well-studied spinel nitrides $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Ge}}_{3}{\mathrm{N}}_{4}$. $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Sn}}_{3}{\mathrm{N}}_{4}$ is a semiconductor with a direct band gap of 1.40 eV and an attractive small electron effective mass of 0.17. Its optical properties are different from that of $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Ge}}_{3}{\mathrm{N}}_{4}$ because of the difference in the conduction band minimum. The Sn $K$, Sn ${L}_{3}$, Sn ${M}_{5}$, and N $K$ edges of the x-ray-absorption near-edge structure spectra in $\ensuremath{\gamma}\text{\ensuremath{-}}{\mathrm{Sn}}_{3}{\mathrm{N}}_{4}$ are calculated using a supercell approach and are found to be rich in structures. These spectra are discussed in the context of the electronic structure of the unoccupied conduction band in the presence of the electron core-hole interaction. These calculated spectra can be used for the characterization of this novel compound.