Electrodeposition of Cu from Acidic Sulphate Solutions in the Presence of PEG - Part II Visible Electroreflectance Spectroscopy Measurements during Electrodeposition

Abstract

This paper reports in situ visible electroreflectance measurements carried out during potentiostatic electrodeposition of Cu from acidic sulphate solutions in the absence and presence of PEG. Time-dependent electroreflectance spectroscopy gives information on the evolution of the electronic structure of the growing film, yielding new insight into the electrocrystallisation mode. Roughness effects and purely optical quantities were separated by operating in a suitable range of visible wavelengths. Optical transients were followed with a simple model correlating the relative spectral reflectivity and the degree of dispersion of Cu crystallites. Electroreflectance data were complemented by Raman surface-enhancement measurements and scanning electron microscopy. Electroreflectance results can be correlated with the surface morphology and with the formation of Cu clusters giving rise to different degrees of Raman surface enhancement.