Formation of Bi 2S 3 thin films on Au(111) by electrochemical atomic layer epitaxy: kinetics of structural changes in the initial monolayers

Abstract

The kinetics and growth mechanism of the first and second monolayers of Bi 2S 3 by electrochemical atomic layer epitaxy (ECALE) has been studied using voltammetry and chronoamperometry techniques. Scan rate dependent cyclic voltammetry experiments reveal that the peak current in the stripping of the S layer from a Bi modified Au(111) electrode is a linear function of a 2/3 power of the scan rate, ν 2/3. Similar behavior is observed for the deposition of Bi on to one atomic layer of an S modified Au(111) electrode. The dissolution of the Bi atomic layer from the S modified Au(111) electrode involves an initial Langmuir-type adsorption–desorption accompanied by a nucleation and two-dimensional (2-D) growth process. When Bi atomic layers are used as a first layer, the nucleation and 2-D growth process was observed for both deposition and stripping. Analysis of the reduced variables demonstrates that the stripping of S from Au(111)Bi and stripping of Bi from Au(111)S fit the progressive model. Our results suggest that the nucleation and 2-D growth mechanism is the dominant process in the formation of Bi 2S 3 atomic layers if Bi is used as the first layer in the ECALE method.