Ge-SiO 2 thin films were prepared by the RF magnetron sputtering technique on p-Si substrates from a Ge -SiO 2 composite target. The asdeposited films were annealed in the temperature range of 300 -1000 8C under nitrogen ambience. The structure of films was evaluated by X-ray diffraction, X-ray photoemission spectroscopy and Fourier transform infrared absorption spectroscopy. Results show that the content of Ge and its oxides in the films change with increasing annealing temperature ðT a Þ; the photoluminescence (PL) characteristics are closely dependent on the contents of Ge and its oxides in SiO 2 matrix. The dependence observed strongly suggests that the PL peak at 394 nm is related to the existence of GeO and 580 nm to that of Ge nanocrystal (nc-Ge) in the films.

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