Formation of CdS nanocrystals in SiO2 by ion implantation

We present a systematic study of the influence of ion dose and post-implantation annealing on the synthesis and growth of CdS nanocrystals in a SiO2 matrix. Nanocrystals were obtained after implantation of monoenergetic Cd and S ions and subsequent annealing in a very wide range of annealing temperatures. T,. The average size, as deter-mined from the blue shift of band gap E-g, varied from 3.5-4.5 to 10 nm, depending on implantation and annealing parameters. For the highest dose. 10(17) ions/cm(2), the synthesis of CdS phase starts already during implantation. For T, above 700 degreesC, large nanocrystals (9-10 nm) prevail for all doses. High energy optical transitions. identified as the E-1A and E-1B transitions of hexagonal CdS, were also observed after annealings at higher temperature. (C) 2002 Elsevier Science B.V. All rights reserved.