Effect of annealing environment on antimony redistribution in pseudomorphic Si/SiGe/Si〈Sb〉 heterostructures

Sb redistribution in an MBE-grown strained Si/Si0.85Ge0.15/Si〈Sb〉 heterostructure was studied by secondary ion mass-spectrometry. Two types of annealing procedures were applied, thermal annealing in vacuum furnace and photon annealing in hydrogen. A simple mathematical model for the quantitative description of the Sb redistribution in multi-layer structures was developed. Diffusivities of Sb in Si and strained Si0.85Ge0.15 were determined by fitting the experimental profiles with calculated ones. Activation energy for Sb diffusion in strained Si0.85Ge0.15 was determined. It was found that, upon annealing in vacuum, Sb atoms diffuse considerably faster than upon photon annealing in hydrogen. This effect was attributed to the decrease in vacancy population due to lowering of the energy barrier for vacancy annealing and/or suppressing of surface vacancy generation.