The Influence of Alkaline Earth Elements on Electronic Properties of α-Si₃N₄ via DFT Calculation

Abstract

We used density functional theory (DFT) calculations to study the influence of alkali earth metal element (AE) doping on the crystal structure and electronic band structure of α-Si₃N₄. The diversity of atomic radii of alkaline earth metal elements results in structural expansion when they were doped into the α-Si₃N₄ lattice. Formation energies of the doped structures indicate that dopants prefer to occupy the interstitial site under the nitrogen-deficient environment, while substitute Si under the nitrogen-rich environment, which provides a guide to synthesizing α-Si₃N₄ with different doping types by controlling nitrogen conditions. For electronic structures, energy levels of the dopants appear in the bottom of the conduction band or the top of the valence band or the forbidden band, which reduces the bandgap of α-Si₃N₄.

Keywords

first-principles / density functional theory calculations / alkaline earth elements doped α-Si₃N₄ / photoluminescence material / crystal structure / electronic structure