Characterisation of thin films of CdS deposited on Ag(111) by ECALE. A morphological and photoelectrochemical investigation

The electrochemical atomic layer epitaxy (ECALE) methodology is a valid and low-cost approach for thin film formation on a metallic substrate. This paper reports on a morphological and photoelectrochemical investigation carried out on CdS samples formed with various numbers of deposition cycles. Ex-situ atomic force microscopy (AFM) measurements showed the attainment of a well-defined morphology, with an almost constant size and density of clusters. The layer-by-layer growth mechanism that is the aim of ECALE methodology, and that is strongly suggested by the electrochemical characterisation, seems to be confirmed. The photoresponse of the material, evaluated in alkaline polysulphide medium, shows a spectral dependence in very good agreement with literature reports for CdS single crystals.