Dynamic-scaling exponents and the roughening kinetics of gold electrodeposits

The kinetics of gold electrodeposit roughening was studied at the nanometer level by scanning tunneling microscopy (STM) and by using dynamic-scaling theory. Gold electrodeposits were grown at 100 nm s^-1 from the electroreduction of hydrous gold oxide layers. The following dynamic-scaling exponents were obtained: {α}(I)=0.90±{}0.06 and {β}(I)=0.31±{}0.08 for Lₛ{L}sc, and α(II)=0.49±0.05 and β(II)=0.51±0.08 for{L}ₛ$>${L}sc$, where ${L}ₛ$ is the scale length, and ${L}sc$ is a critical length closely related to the average grain size of the electrodeposit measured from STM imaging. Results from dynamic-scaling analysis are consistent with a grain surface smoothing mechanism involving surface diffusion of gold atoms.