Electrodeposition of lead was studied in the system n-Si(lll)/Pb2+, Cl
O4-, H+ using cyclic voltammetry, chronoamperometry, ex situ optical m
icroscopy and in situ scanning probe microscopy (SPM). Comparative stu
dies were also performed in the system HOPG(0001)/Pb2+, ClO4-, H+. No
underpotential deposition (UPD) of 2D Pb phases could be observed in t
he investigated systems indicating a weak substrate-deposit interactio
n. In both systems Pb deposition occurs in the overpotential range (OP
D) via a 3D island growth on an unmodified substrate according to the
Volmer-Weber growth mechanism. At relatively low overpotentials the el
ectrodeposition reaction is mainly initiated on substrate surface inho
mogeneities such as steps. The initial deposition kinetics in the OPD
range is controlled by a progressive nucleation on active sites and a
hemispherical diffusion towards the growing Pb clusters. The nucleatio
n rate and the number of atoms in the critical cluster (nucleus) are d
etermined from the analysis of the kinetic data. Results are compared
with previous data for 3D Pb phase formation on UPD modified silver si
ngle crystal substrates. (C) 1998 Published by Elsevier Science Ltd. A
ll rights reserved.