Microstructural and photoluminescence studies of germanium nanocrystals inamorphous silicon oxide films

Ge nanocrystal growth in amorphous silicon oxide film was studied using the transmission electron microscopy and x-ray photoelectron spectroscopy tech niques. The as-sputtered sample contained mainly GeO2 and Ge suboxides. GeO 2 and/or suboxides dissociate when rapid thermal annealed and provide Ge fo r nanocrystal formation. Nanocrystals of similar size (similar to 60 Angstr om in diameter) were obtained when annealed at 800 degreesC. Nanocrystals w ith diameters of 200-280 Angstrom consisting of multiple twin structures ne ar the Si-SiO2 interface were observed when annealed at 1000 degreesC. The twin structure was attributed to the enhanced diffusion of Ge at 1000 degre esC and the short annealing time. Our photoluminescence (PL) results show t hat the best PL response was obtained with samples that exhibit uniform nan ocrystal size. (C) 2001 American Institute of Physics.