Quasi-particle band structure and enhanced excitonic effect of silicane by using GW and BSE calculation

The authors present first-principles calculations of the quasiparticle correction and the optical absorption of chairlike silicane fully hydrogenated silicene by using GW method and Bethe-Salpeter equation (BSE). Electron-electron interaction significantly affects the band structure of chairlike silicane. The indirect band gap of chairlike silicane increases from 2.08 to 3.53 eV and the direct quasiparticle band gap increases from 2.44 to 3.85 eV upon inclusion of the quasiparticle correction. Electron-hole interaction significantly affects the optical absorption of chairlike silicane. The binding energy of the binding exciton is about 0.40 eV, much larger than the value of 15 meV in the bulk Si. The enhanced excitonic effect is expected to be of importance in optoelectronic applications of silicene-based nanostructures.