Morphological instability and additive-induced stabilization in electrodeposition

Experiments show that electrodeposited (ED) films exhibit rough surfaces unless the electrochemical bath contains small quantities of molecular "additive" species. We develop a model for ED with additives which shows the suppression of the morphological instability by preferential additive accumulation near surface protrusions due to complex formation and additive codeposition, and subsequent growth site blocking. Linearly stable growth can be achieved over a wide range of deposition flux at sufficiently large additive bulk concentration. We predict the growth conditions necessary for level surfaces, in good agreement with experiments.