ANNEALING EFFECTS ON SELFASSEMBLED Ge/Si (100) ISLANDS PREPARED BY ION BEAM SPUTTERING

Effects of annealing on the evolution of self-assembled Ge/Si (100) islands grown by ion-beam sputtering were investigated by atomic force microscopy. The islands with high aspect ratio (0.2-0.33) and small diameter (45-75 nm) without annealing were observed. Significant evolutions occur on islands number density, shapes and aspect ratio with the changes of the annealing time and Ge coverage. Increasing annealing duration, the density and aspect ratio decreased with a simultaneous increase of the average volumes at low deposition coverage. Comparing with it, the density and aspect ratio increased during the annealing of the samples with high deposition coverage. No pyramid islands were observed in our samples. Atom diffusion and the poor crystalline Si buffer confirmed by the Raman spectrum measurement led to these results.