Fabrication and characterization of GexAl1−x thin films

Abstract Ge x Al 1−x films were prepared by co-sputtering Al and Ge targets in a dual-magnetron rf/dc sputtering system. Films with composition across the binary phase diagram were fabricated. Transmission electron microscopy and X-ray diffraction analyses of the films indicate a metastable single phase to an equilibrium two phase to a granular microstructure transition with the decrease in the Ge concentration. Nanostructured granular films were obtained at low Ge concentrations. The granularfilms have grain size ranging between 20 and 100 nm. XPS analyses indicate the presence of small amounts of oxygen in the films, perhaps from the residual gases in the system or from the targets, but only Al gets preferentially oxidized, especially at high Al concentrations. Ge, regardless of concentration, remains essentially in elemental form.