Embedded SiGe nanoparticles formed by atom beam co-sputtering of Si, Ge, SiO2

Using atom beam co-sputtering of SiO2, Ge and Si targets, composite films containing Si, Ge and SiOx at different compositions were prepared and annealed at different temperatures. The influence of annealing temperatures on phase formation in the composite films was studied. The films were characterized using UV–vis absorption spectroscopy, FTIR, and GXRD. GXRD plots show diffraction peaks due to SiGe alloy nanoparticles and no peaks due to elemental Si or Ge. The nanoparticle size estimated from GXRD is 4.7 nm. UV–visible spectra show the red shift in absorption edge as the annealing temperature is increased. FTIR spectra reveal phase separation of SiGe alloy from SiOx matrix, upon annealing.