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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. [Copyright &y& Elsevier]

Abstract: The attainment of ultrathin films of well ordered II–VI and III–V compound semiconductors is an active research area of the electrochemistry group at the University of Florence. The method employed is the electrochemical atomic layer epitaxy (ECALE) which is based on self limiting reactions such as underpotential deposition (UPD). Recently, the possibility of combining the electrodeposition at nanometer scale and the self assembly phenomena has been investigated. In particular, the ECALE method was used to deposit CdS on Ag(111) covered by a patterned hexadecanthiol (HDT) self assembled monolayer (SAM). In fact, the deposition of CdS only takes place on the uncovered silver substrate, whereas it is not possible on the thiols monolayers. The deposits have been characterized by electrochemical techniques and AFM measurements. [Copyright &y& Elsevier]