Microstructural and photoluminescence studies of germanium nanocrystals in amorphous silicon oxide films

Ge nanocrystal growth in amorphous silicon oxide film was studied using the transmission electron microscopy and x-ray photoelectron spectroscopy techniques. The as-sputtered sample contained mainly GeO2 and Ge suboxides. GeO2 and/or suboxides dissociate when rapid thermal annealed and provide Ge for nanocrystal formation. Nanocrystals of similar size (similar to 60 Angstrom in diameter) were obtained when annealed at 800 degreesC. Nanocrystals with diameters of 200-280 Angstrom consisting of multiple twin structures near the Si-SiO2 interface were observed when annealed at 1000 degreesC. The twin structure was attributed to the enhanced diffusion of Ge at 1000 degreesC and the short annealing time. Our photoluminescence (PL) results show that the best PL response was obtained with samples that exhibit uniform nanocrystal size. (C) 2001 American Institute of Physics.