Electrodeposition of copper on copper single crystal (100) face in presence of chloride ions

Abstract

Observations of copper electrodeposits on to the (100) plane of copper was made from highly purified solutions of copper sulphate containing known concentration of hydrochloric acid from 10−10 to 10−1 m/L. In pure solutions at current densities of 5 and 10 mA/cm.2 layers and pyramids were noticed. In the presence of hydrochloric acid of concentration 10−9 to 10−5 m/L there is a gradual decrease of distance between successive steps. At 10−4 m/L of HCl there was the breaking of layers giving rise to ridge type of growth. With the increase of concentration to 3·5×10−3 m/L pyramids appear again. On increasing the concentration of HCl to 10−2 m/L there was the formation of triangular pyramids of cuprous chloride and on still increasing the concentration, polycrystalline type of deposit was noticed. The transition from layer to ridge, ridge to pyramids and to polycrystalline deposit occurs at all c.d. studied but the critical concentration of HCl needed for the transition depends upon the current density.