ELECTROCHEMICAL ATOMIC LAYER EPITAXY DEPOSITION OF CDS ON AG(111) - AN ELECTROCHEMICAL AND STM INVESTIGATION

The electrochemical atomic layer epitaxy methodology was employed to o btain CdS deposits on Ag(lll) by alternate underpotential deposition o f up to five layers of sulfur and four layers of cadmium. The charge i nvolved in each layer was determined by cyclic voltammetry. With the e xception of the first sulfur layer, the charge involved in the deposit ion of each sulfur and cadmium layer was the same, indicating the achi evement of a stoichiometric, 1:1 ratio, deposit from the second layer. The first layer, which consisted of sulfur on the bare silver surface , involved a higher charge and is to be regarded as an interface betwe en the metal and the compound. The measured charge is in good agreemen t with that estimated on the basis of STM images. The structure reveal ed by STM for all but the first layer was a (root 7 x root 7)R19.1 deg rees, with one atom per lattice site, relative to the Ag(lll) substrat e.