Effect of indium tin oxide substrate roughness on the morphology, structural and optical properties of CdS thin films

Indium tin oxide (ITO) coatings of glass substrates were etched with hydroc hloric acid in order to obtain different root-mean-square roughness (R-ITO) on its surface. The effect of R-ITO on the morphology, structural and opti cal properties of CdS films deposited was investigated. Polycrystalline cad mium sulfide thin films were deposited on ITO/glass substrates by chemical- bath deposition (CBD) at 358 K, and studied by atomic force microscopy (AFM ). Roughness of CdS films (R-CdS) showed a nearly linear increase with R-IT O. The thickness of CdS films was investigated by Auger Electron Spectrosco py (AES) and showed an increment with R-CdS. X-ray diffraction results show ed that CdS films have a cubic zincblende structure with a(lll) preferred o rientation. The measured residual strain of the CdS films showed an initial increse with R-ITO reaching a maximum point at 15 +/- 2 nm, and after that exhibited a decreasing dependence. The optical band gap E-o of the CdS fil ms obtained from transmittance measurements did not depend on R-ITO. (C) 20 00 Elsevier Science B.V. All rights reserved.