Nucleation and Growth of Extremely Thin CdSe Films Electrodeposited from Near-Neutral Electrolytes

We report on nucleation and growth of CdSe thin films electrodeposited onto F:SnO2-coated glass (FTO) under weakly basic pH conditions. Chronoamperometry and electron microscopy reveal that nucleation sites grow three-dimensionally, coalesce, and form a dense film following the Volmer-Weber growth mechanism. Nucleation and growth were studied as a function of bias potential over the range of -0.95 V to -1.15 V. Fitting a two-rate model to current transients at different potentials shows that more negative bias potentials leads to larger nucleation densities and growth rates. Larger nucleation density results in coalescence at smaller thickness and in more uniform thin coatings, which are important for CdSe thin film applications such as extremely thin absorber solar cells. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.052210jes] All rights reserved.