PROPERTIES OF CADMIUM-SULFIDE THIN-FILMS DEPOSITED BY CHEMICAL BATH DEPOSITION WITH ULTRASONICATION

Ultrasonic agitation was applied during the chemical bath deposition o f CdS thin films. Ultrasonication resulted in a dramatic difference in surface morphology, growth rate, and optical properties of CdS films. There were virtually no colloidal particles adsorbed on the surface. The surface roughness measured by atomic force microscopy was reduced by a factor of two. Band gap energy increased to 2.39 eV from 2.37 eV. X-ray patterns showed that the preferred orientation changed from hex agonal(002)/cubic(111) to hexagonal(101). Optical transmission improve d in the wavelength range longer than 520 nm. The chemical reaction fo r CdS formation started at a lower temperature under ultrasonication, and dense films were obtained even when the chemical composition of th e aqueous solution deviated far from the optimum conditions. (C) 1998 Elsevier Science Ltd. All rights reserved.