Interdiffusion at Si/SiGe interface analyzed by high-resolution X-ray diffraction

The interdiffusion at Si/SiGe interface with Ge mole fraction of 19.2%, and SiGe layer thickness of 283 nm was studied by high-resolution X-ray diffraction. The results showed that the obvious fringes of rocking curve obtained from pre-annealing sample faded out gradually and disappeared completely with increasing annealing temperature and prolonging annealing time, indicating that the interface was broadened gradually due to the interdiffusion. The angular separation between the SiGe and Si peaks gradually decreased, suggesting that a high temperature promoted the interdiffusion related to the strain relaxation and the change of Ge composition. The interdiffusivity was calculated from the decay of the integrated intensity of the SiGe peaks as a function of annealing time at different temperatures. After annealing the scattering distributions of Si substrate and SiGe film in both ω and 2θ/ω scans in (113) reciprocal space maps spread greatly from a very narrow in pre-annealing sample, indicating the formation of mosaic structure and the destruction of fully commensuration with the substrate.