Control of Semiconductor Particle Size in Sol-Gel Thin Films

Thin silica and silica-titania films containing CdS and PbS quantum size particles were obtained by separate preparation of the matrix and the colloidal sols and successive mixing. Sulfide particles were obtained by reaction of metal acetates with thioacetamide and control of particle size was achieved by surface capping agents. Powders and thin films deposited on soda-lime slides were prepared and characterized by XRD. Absorption spectra were recorded on films. The nonlinear refractive index was measured by an m-line technique on a CdS-doped sample. The nonlinear effect was found to be reversible and a n2 value of -3 10-9 cm2/kW was measured.