First-principles investigation of visible light emission from silicon-based materials.

Abstract

The atomic and electronic structure of various Si-based layered structures is calculated using pseudopotential density-functional theory and a self-energy approach. A silicon-hydrogen compound, consisting of a stacking in the [111] direction of double layers of Si terminated with H, is found to have an almost direct band gap of 2.75 eV. Substituting OH groups for H atoms leads to the compound siloxene, which is found to have a direct band gap of ∼1.7 eV. Investigations of the band-edge states and calculations of matrix elements show that these direct transitions are very strong