Rough Growth and Morphological Instability of Compact Electrodeposits

We have investigated the initial stage of growth in electrochemical deposition at low constant currents in quasi-2D strip geometry. We used $0.5M$ aqueous solutions of CuSO₄, and current densities ranging between 20 and 100mAcm^-2. We monitored the morphology of the growing interface and the electrical parameters of the system. We find two different growth regimes: at short times the interfaces show roughness scaling with a roughness exponent, α0ex0ex=0ex0ex0.78±0.05; at longer times a morphological instability develops whose characteristic time and length scales compare well with those expected from a Mullins-Sekerka instability.