Annealing effects on self-assembled Ge/Si (100) islands prepared by ion beam sputtering deposition

Abstract

The effects of annealing on the evolution of self-assembled Ge/Si (100) islands grown by ion beam sputtering deposition were investigated by atomic force microscopy. Islands with high aspect ratio (AR, 0·2–0·33) and small diameter (45–75 nm) without annealing were observed. Significant evolutions occur on the islands’ number density, shapes and AR with the changes in annealing time and Ge coverage. With increasing annealing duration, the density and AR decreased with a simultaneous increase in average volumes at low deposition coverage. In comparison, the density and AR increased during the annealing of samples with high deposition coverage. No pyramid islands were observed in our samples. Atom diffusion and a mix crystal interface including amorphous and crystal components confirmed by Raman spectrum measurement led to these results.