Electrodeposition of Bi thin films on n-GaAs(111)B. II. Correlation between the nucleation process and the structural and electrical properties

Abstract

The surface morphology and the crystal structure of 40 nm thin Bi films electrodeposited on GaAs(111)B at different growth overpotentials have been studied by means of atomic force microscopy and X-ray diffraction, respectively. The Bi/GaAs interface has also been electrically characterized by means of current-voltage curves that have been analyzed with the thermionic-field emission theory. Taking into account the results presented in Part I, we can conclude that the structural and electrical properties of the Bi layers are correlated with the nucleation process and, therefore, with the energy band diagram of the semiconductor-electrolyte interface. We have found that surface morphology is directly dependent on the amount of protons adsorbed on the GaAs surface, whereas the crystal quality and the interfacial properties also depend on the nucleation mechanism (instantaneous or progressive).