Stable interface dynamics for copper electrodeposition in the presence of organic additives: Evidence for a gas-like surface state of the organic adsorbate

摘要

The interface dynamics of metal electrodeposits in the presence of organic additives is followed in two-dimensional glass cells. Stable Cu interfaces are formed at intermediate thiourea concentrations when a critical, but small surface coverage of thiourea (theta) is reached. For theta values corresponding to a close-packed adsorbate, the interface again becomes unstable because Cu growth takes place at defective sites in the adsorbed layer. The ability of additive molecules to suppress unstable growth is related to the formation of a diluted two-dimensional gas-like surface state preferentially adsorbed at protrusions. Protrusions are more efficient for capturing the additive than valleys, as additive molecules arrive at the growing deposit under diffusion control from the solution. [References: 22]