“Stable Interface Dynamics for Copper Electrodeposition in the Presence of Organic Additives: The Evidence of a Gas-Like Surface of the Organic Adsorbate”

P.L. SCHILARDI; O. AZZARONI; R.C. SALVAREZZA

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2000 p. 13098 - 13103

0163-1829

The interface dynamics of metal electrodeposits in the presence of organic additives is followed in twodimensional glass cells. Stable Cu interfaces are formed at intermediate thiourea concentrations when a critical, but small surface coverage of thiourea ~ u! is reached. For uvalues 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 twodimensional 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.