Surface modification of CdS nanocrystallites doped in SiO2 matrix

Abstract

Nanometer-sized CdS semiconductor particles were prepared by pulsed laser deposition (PLD) and dispersed in SiO2 matrix. Surface modification of the CdS nanocrystallites deposited with the SiO2 material on a substrate caused the generation of CdO composite, which formed an encapsulating shell layer surrounding the inner CdS crystallite. Raman and photoluminescence (PL) analyses clearly identified and characterized this component. Annealing of the film caused growth in size of the CdO shell as established from the redshift of its PL band gap emission. This growth was found to keep in unison with the corresponding inner CdS crystalline growth, and a possible mechanism is suggested. Finally, through proper selection of the substrate temperature during PLD to remove crystalline stress, it was possible to obtain a complete optimum CdS profile without the accompanying CdO formation or characteristics. © 2001 American Institute of Physics.