Interdiffusion of Ge/Si in GeSi dots, grown onto Si (001) substrates by gas-source molecular beam epitaxy, was investigated. Transmission electron microscopic images showed that, after annealing, the height/base-diameter aspect ratio had increased. Raman spectra showed that the Si-Ge mode red-shifted and the intensity of the local Si-Si mode increased with increasing annealing temperature; thus suggesting the occurrence of Ge/Si interdiffusion during annealing. Photoluminescence peaks from the dots and wetting layers exhibited a blue-shift, due to atomic intermixing during annealing. The interdiffusion thermal activation energies of the GeSi dots and wetting layers were equal to 2.16 and 2.28eV, respectively (figure 2). The interdiffusion coefficient of the dots was about 40 times higher than that of wetting layers.

Ge/Si Interdiffusion in the GeSi Dots and Wetting Layers. J.Wan, Y.H.Luo, Z.M.Jiang, G.Jin, J.L.Liu, K.L.Wang, X.Z.Liao, J.Zou: Journal of Applied Physics, 2001, 90[8], 4290-2

Figure 2

Interdiffusion in GeSi/Si