Structural and optical studies of CdS nanocrystals embedded in silicon dioxide films

Silicon dioxide films doped with nanocrystallites of CdS with a mean radius value in the range of 20 to 40 Angstrom have been grown using the magnetron rf-sputtering technique. We have studied the combined effects of rf-power deposition, the number of semiconductor chips on the SiO2 target, and post-annealing temperature on the CdS crystal size. The optical transmission spectra display a marked blue shift of the absorption band edge of up to 400 meV which was attributed to quantum size confinement effects. The luminescence spectra show a narrow emission peak tentatively explained as being due to the recombination of electrons on shallow donor levels with confined valence band holes. (C) 1998 Elsevier Science S.A.