Ge/Si interdiffusion in the GeSi dots and wetting layers

The Ge/Si interdiffusion in GeSi dots grown on Si (001) substrate by gas-so urce molecular beam epitaxy is investigated. Transmission electron microsco py images show that, after annealing, the aspect ratio of the height to bas e diameter increases. Raman spectra show that the Si-Ge mode redshifts and the intensity of the local Si-Si mode increases with the increase of anneal ing temperature, which suggests the Ge/Si interdiffusion during annealing. The photoluminescence peaks from the dots and the wetting layers show blues hift due to the atomic intermixing during annealing. The interdiffusion the rmal activation energies of GeSi dots and the wetting layers are 2.16 and 2 .28 eV, respectively. The interdiffusion coefficient of the dots is about 4 0 times higher than that of wetting layers and the reasons were discussed. (C) 2001 American Institute of Physics.