Raman and optical transmission spectra of GaSb–SiO 2 composite films fabricated by radio frequency magnetron co-sputtering

Abstract

The composite films of GaSb–SiO 2 fabricated on the glass substrate by radio frequency magnetron co-sputtering technique have been studied by Raman and optical transmission spectra. Transmission electron microscopy and X-ray diffraction patterns confirm the existence of GaSb nanocrystals in the SiO 2 matrices. The average size of GaSb is in the range of 4.1–11.0 nm. Room temperature Raman spectra show that the Raman peak of GaSb–SiO 2 composite films have a larger red shift than that of bulk GaSb because the phonon confinement effect and the tensile stress affect thermal expansion and lattice mismatch between GaSb and SiO 2. Room temperature optical transmission spectra show that the optical absorption edge exhibits a very large blue shift of 2.71 eV with respect to that of bulk GaSb, which is mainly explained by the quantum confinement effect.