Electronic and optical properties of silicon based porous sheets

Abstract

Si based sheets have attracted tremendous attention due to their compatibility with the well-developed Si-based semiconductor industry. On the basis of state-of-the-art theoretical calculations, we systematically study the stability, electronic and optical properties of Si based porous sheets including g-Si₄N₃, g-Si₃N₄, g-Si₃N₃ and g-Si₃P₃. We find that the g-Si₃N₃ and g-Si₃P₃ sheets are thermally stable, while the g-Si₄N₃ and g-Si₃N₄ are unstable. Different from the silicene-like sheets of SiN and Si₃N which are nonplanar and metallic, both the porous g-Si₃N₃ and g-Si₃P₃ sheets are planar and nonmetallic, and the former is an indirect band gap semiconductor with a band gap of 3.50 eV, while the latter is a direct band gap semiconductor with a gap of 1.93 eV. Analysis of the optical absorption spectrum reveals that the g-Si₃P₃ sheet may have applications in solar absorbers owing to its narrow direct band gap and wide range optical absorption in the visible light spectrum.