QUANTUM CONFINEMENT IN NANOSTRUCTURED CDNITE COMPOSITE THIN-FILMS

Cd1-xNixTe nanostructured thin films have been deposited using the rad io frequency sputtering technique. Films are formed by sphericallike m icrocrystallites with a broad grain size distribution. The measured na nocrystallite average diameters were 35, 30, and 26 nm corresponding t o the films with Ni concentrations of 5%, 10%, and 15%, respectively. The film structure was zincblende,? resembling the crystalline structu re for bulk CdTe. Particle-size effects were observed in the optical a bsorption spectra. As the Ni content in the films increases, the grain size diminishes, and the optical band gap (E-g) energy shows a blue s hift at a rate of about 7.5 meV/at. %, for Ni concentrations up to 15 at. %. Alloying effects additional to quantum confinement effects are discussed. The E-g shifts due to quantum confinement have been found t o fall in the intermediate regime between strong and weak confinement. The quantum yield for the photoluminescence peak increases as the par ticle size decreases, probably as a result of exciton recombination en hancement due to batter nanocrystallites quality. (C) 1997 American In stitute of Physics.