Electrodeposition of PbS Multilayers on Ag(111) by ECALE V.C.Fernandes a , E. Salvietti b , F. Loglio b , M. Innocenti b , L. H. Mascaro a and M. L. Foresti b a Departamento de Química, Universidade Federal de São Carlos, Caixa Postal 676, São Carlos - SP, 13565-905, Brazil. b Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy Lead sulfide (PbS) thin films were grown on single crystal Ag(111) substrate. PbS films were obtained by Electrochemical Atomic Layer Epitaxy (ECALE) method, that is by alternated underpotential deposition (UPD) of lead and sulfur. The voltammetric analysis of the first Pb UPD and S UPD peaks indicates a mechanism of two-dimensional growth, which is consistent with epitaxial growth. Electrochemical stripping measurements indicate that amount of Pb and S deposited in a given number of cycles is a function of the number of cycles employed, again suggesting a layer-by-layer growth. The stripping charges associated with each layer of Pb and S was 87 µC cm -2 . This result suggests that amount of Pb and S in these films corresponds to the stoichiometric 1:1 ratio, indicating the formation of a compound. Introduction Binary semiconductors are considered as important technological materials because of their potential applications in optoelectronic devices, solar cells, IR detectors and lasers (1, 2). Binary compounds of group IIB and group VIA elements, commonly referred to as II-VI compounds, have technologically important applications. Thin films of these compounds are usually prepared by vacuum evaporation, chemical vapor deposition, sputtering and spray pyrolysis method [ 3 , 4 ]. However the properties of semiconductors depend on dimension and supperlattice structure and the film must be highly crystalline and have a single crystallographic orientation. Therefore, the possibility of controlling the growth processes at an atomic or a molecular level is becoming more and more important, with an increasing emphasis on the nanometric structures. The atomic layer processes allow the precise control of the deposit thickness and composition what results that this technique is quite promising in the obtaining of these semiconductor thin films. Electrochemical Atomic Layer Epitaxy (ECALE), developed by Stickney (5), has been used to produce a wide variety of well-ordered semiconductor deposits under ambient pressure and temperature (6-12). With Electrochemical Atomic Layer Epitaxy, a monolayer of the compound is obtained by alternating the underpotential deposition of the metallic element with the underpotential deposition of the non-metallic element in a cycle. The largest advantage of this method is that the individual steps of each cycle can be examined and optimized independently. That means that the conditions for deposition can be adjusted as concerns potentials, pH, reactants, and so on. These conditions are dependent on the compound one wants to form, and on the substrate used. Lead sulfide (PbS) has been one of the binary semiconductors of the group II-VI that have received considerable attention because of its variety of applications. PbS with its ECS Transactions, 11 (7) 279-286 (2007) 10.1149/1.2779091 ©The Electrochemical Society 279 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 54.221.180.8 Downloaded on 2016-10-31 to IP