Atomic structure, electronic and optical properties of Si nanocrystals embedded in β-cristobalite and α-quartz

We use DFT calculations to study the atomic structures, the optical and electronic properties of silicon nanocrystals (nc-Si) embedded in β-cristobalite and in α-quartz matrix. We show that the optical properties are influenced by the matrix type. The energy range of the absorption spectrum of nc-Si in α-quartz matrix is more extended than that of nc-Si in β-cristobalite. The presence of Si-O-Si bridge bonds at the nc-Si/β-cristobalite interface favours the stability of the system. The energy gap of nc-Si with interface defects is larger than that of nc-Si without interface defects.