Raman characterization of strain and composition in small-sized self-assembled Si/Ge dots

摘要: A detailed Raman characterization of the structural properties as-grown and annealed self-assembled Si/Ge dot multilayers is reported in this paper. Several new modes or dots a frequency splitting 4.2 cm(-1) between longitudinal (LO) transversal optical (TO) Ge-Ge are observed spectra. An average Ge content 0.8 lateral strain -3.4% consistently obtained from these spectral features for with size about 20 nm height 2 nm. It suggests that certain amount intermixing Si spacer layers takes place multilayers. The annealing behavior Ge-Si mode indicates sharp alloy within core regions dots, rather than interface dots. phonon strain-shift coefficients determined small-sized high under biaxial condition. results show LO-TO frequencies can be used as an efficient way to determine composition uncorrelated which mean field close case.