Preparation and Optical Properties of Nanocrystalline Ga_0.62In_0.38Sb Embedded in SiO₂ Composite Films

Nanocrystalline Ga_0.62In_0.38Sb embedded in SiO₂ matrix has been fabricated by radio frequency magnetron cosputtering. X-ray photoelectron spectroscopy strongly supports the existence of nanocrystalhe Ga_0.62In_0.38Sb embedded in SiO₂ matrix. The room-temperature Raman spectrum shows that the Raman peaks of the Ga_0.62In_0.38SbSiO₂ composite film have a larger red shift of about 95.3cm^-1 (longitudinal-optic) and 120.1 cm^-1 (transverse-optic) than those of the bulk GaSb. This can be explained by the phonon confinement and tensile stress effects. The room-temperature optical transmission spectra show that the absorption edge exhibits a large blue shift of about 2.43 eV compared with that of the bulk semiconductor, suggesting the existence of quantum size effects.