Optical properties of nanocrystalline Ga1−xInxSb/SiO2 films

Ga1−xInxSb (x=0.19, 0.38, 0.63) nanoparticles embedded in a SiO2 matrix were grown on the glass substrates by radio-frequency magnetron co-sputtering. X-ray diffraction patterns strongly support the existence of nanocrystalline Ga1−xInxSb in the SiO2 matrix. The changes in binding energies with Ga1−xInxSb nanocrystals deposition have been directly observed by X-ray photoemission spectroscopy, and these show the existence of Ga1−xInxSb nanocrystals in the SiO2 matrix. Room-temperature Raman spectra show that the Raman peaks of the Ga1−xInxSb–SiO2 composite film have a larger red-shift of about 95.3 cm−1 (longitudinal-optical mode) and 120.1 cm−1 (transverse-optical mode) than that of bulk GaSb, suggesting the existence of phonon confinement and tensile stress effects. Additionally, the room-temperature optical transmission data exhibit a large blue-shift with respect to that of the bulk semiconductor due to the strong quantum confinement effect.