Study of the Oxidation of Polycrystalline SiGe: Formation of Ge Nanocrystals and their Related Luminescence

Polycrystalline SiGe layers have been oxidized in either dry or wet atmospheres. The evolution of the growing oxides and the SiGe layer during the oxidation processes have been characterized using Raman spectroscopy, X-ray diffraction, Rutherford backscattering and Fourier transform infrared spectroscopy. Formation of Ge nanocrystals has been observed for both oxidation atmospheres. Violet luminescence emission has been observed and its relation to the oxidation processes has been studied. The luminescence is unambiguously related to the presence of these Ge nanocrystals. Since it does not exhibit quantum confinement, it must be related to defects linked to the nanocrystals.