Intrinsic origin of visible light emission from silicon quantum wires: Electronic structure and geometrically restricted exciton

Abstract

We theoretically investigate excitonic effects on the optical properties of silicon quantum wires, based on ab initio electronic structure calculations. The Si wires have a direct, allowed band gap in the visible energy range and exhibit a strong optical anisotropy. Taking into account the electron-hole Coulomb interaction, the geometrical restriction of excitons dramatically enhances the oscillator strength of the optical transitions. Comparisons with recent experimental results are also made.