A combined scanning tunneling microscopy and electrochemical study of copper electrodeposition from a cyanide solution on a zinc alloy

The electrodeposition of Cu on zinc alloy diecast from a cyanide bath was s tudied using electrochemical techniques and scanning tunneling microscopy ( STM) imaging. As the current density ii) is changed from 1 to 30 mA cm(-2), the root mean square roughness of the deposit (xi) first increases, reachi ng a maximum value at j = 10 mA cm(-2), and then decreases. This behavior i s explained by the strong interference of the hydrogen evolution reaction a t the highest current densities. The dynamic scaling theory applied to the STM images for the advanced stages of Cu electrodeposition obtained at j = 10 mA cm(-2) leads to a roughness exponent a = 0.80 and growth exponent bet a > 0.5 consistent with an unstable interface evolution. The addition of so dium selenite promotes a leveling effect by hindering the growth of instabi lities, leading to an interface evolution consistent with the predictions o f thr Edwards-Wilkinson growth model. (C) 2000 The Electrochemical Society. S0013-4651(99)07-122-0. All rights reserved.