Abstract

Pressure-tuned resonant Raman scattering was used to determine the bandgap shift due to quantum size effects of microcrystallite CdS in glass composites and colloids. The phase transition behavior in microcrystallite CdS systems is quite different from that in bulk CdS. We attribute the different behavior to the large number of defects (vacancies) in microcrystallite CdS systems. Then we systematically investigated these defect properties in terms of their pressure coefficients by means of the photoluminescence peaks in CdS microcrystallite systems. We have demonstrated that the main defects in the CdS-glass composites are cadmium vacancies, V_cd; and there are V_cd, V_s, I_s and S_cd defects in the CdS colloids. We expect that the nonlinear-optical properties of CdS microcrystallite systems are greàtly influenced by the excitons bound to these defects.

© 1990 Optical Society of America