Luminescence studies of CdS spherical particles via hydrothermal synthesis

The spherical particles of CdS consisting of nanoparticles (similar to 100 nm) were synthesized by a hydrothermal process. The particle formation and growth depend on the rate of sulfide-ion generation and diffusion-controlle d aggregation of nanoparticles. As demonstrated in the profiles of powder X -ray diffraction, the crystalline phases are governed by the reaction tempe rature. Photoluminescence studies on CdS particles show two emission bands at the room temperature. The red emission at 680 nm is due to sulfur vacanc ies, and a new infrared red (IR) emission at 760 nm is attributed to self-a ctivated centers. A red shift of IR band with the decrease of temperature w as explained with a configurational coordinate model. The different saturat ion limits for the red and IR bands are discussed in terms of the formation of donor-acceptor pairs and exciton in CdS particles. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.