Effect of density of CdTe nanoparticles on the structural and optical properties of TiO2 thin films prepared by rf magnetron sputtering

CdTe nanocrystals with varied volume fraction (V f ∼50-70%) and crystallite size (6-27 nm) embedded in TiO 2 thin films were prepared at different substrate temperatures by rf magnetron co-sputtering technique. The films were mainly amorphous in nature, however, few crystalline features were realized for high density film prepared at higher substrate temperature. The concentration of CdTe nanoparticles had a marked influence on the optical absorption behavior of CdTe:TiO 2 composite thin films. The band-edge shifts of the optical absorption edge with respect to the bulk semiconductor agreed well with the strong confinement regime for single particle confinement. High density CdTe films deposited at different substrate temperatures were found to be Cd-rich as elucidated by XPS studies.