Both the conventional pyrolytic and laser-photochemical growth of amorphous and polycrystalline Ge-Si alloy thin films on various substrates have been investigated. Bulk and thin-film studies have determined the characteristic three-peak Raman spectrum of Ge-Si alloys. The spectrum consists of peaks near 300, 400, and 500 cm-1 corresponding to local modes of Ge-Ge, Ge-Si, and Si-Si atoms, respectively. The peak positions, widths, and intensities are dependent on the alloy composition, crystallinity, and homogeneity. In addition, the peak positions are influenced by the degree of strain in the alloy film. The films have been analyzed ex situ by Raman scattering and Auger electron spectroscopy.