Thin film properties of germanium oxide synthesized by pulsed laser sputtering in vacuum and oxygen environments

Germanium oxide thin films were deposited on Si substrates at ambient temperature using pulsed laser sputtering of GeO2 targets in both vacuum and oxygen environments. The structure and composition of these films were deduced from infrared transmittance and Auger electron spectroscopy measurements. The film properties were strongly influenced by the pressure of the background reactive gas and the laser fluence during deposition with O2. The vacuum deposited films had a low oxygen content and the film’s stoichiometry varied from metal rich at the center to oxidelike near the edges of the film. The films deposited in oxygen appeared stoichiometric and they showed no content variation with radius. Ellipsometry studies indicated, however, that the oxygen grown films were porous. The trends observed in growing these films under various conditions are discussed with respect to potential reaction kinetics in the plume and gas expansion phenomena.