Chemical Bath Deposition of CdS Thin Films: Electrochemical In Situ Kinetic Studies

Abstract

Chemical bath deposition of cadmium sulfide thin films from ammonia/SC(NH2)2/CdSO4 solutions has been studied. in situ using electrochemical open-circuit potential change (EOCPC) measurements. An explanation of the EOCPC dependence with film thickness in terms of space-charge region theory has been reported. The effect of various parameters on the growth and on the film quality is presented (temperature, concentration of reacting species, and film thickness). The structural and electrical properties of CdS thin films prepared by this method have been studied. The x-ray diffraction analysis shows evidence that the orientation perpendicular to the substrate surface is highly preferential confirming that the growth evolves from nucleation on the substrate. From resistivity and EOCPC measurements the following values of the electrical properties of the material have been obtained: dark conductivity about 10-7 (Ωt cm)-1, photoconductivity about 10-2 (Ω cm)-1, carrier concentration about 1013 cm-3, and carrier mobility about 2 cm2 V-1 s-1. © 1991, The Electrochemical Society, Inc. All rights reserved.