The growth of Ge nanocrystals in amorphous SiO2 films was studied by means of transmission electron microscopy and X-ray photo-electron spectroscopy. The as-sputtered samples contained mainly GeO2 and sub-oxides. These dissociated during rapid thermal annealing and provided Ge for nanocrystal formation. Nanocrystals of similar size (6nm-diameter) were obtained upon annealing at 800C. Nanocrystals with diameters of 20 to 28nm, which consisted of multiple twin structures, were observed upon annealing at 1000C. The twin structure was attributed to the enhanced diffusion of Ge at 1000C, and to the short annealing time.

Microstructural and Photoluminescence Studies of Germanium Nanocrystals in Amorphous Silicon Oxide Films. W.K.Choi, Y.W.Ho, S.P.Ng, V.Ng: Journal of Applied Physics, 2001, 89[4], 2168-72