Dynamics of the wetting-induced nanowire reconstruction of Au/Ge(001)

We have used low-energy electron microscopy and scanning tunneling microscopy to visualize the dynamics of the formation of one-dimensional Au-induced nanowires on a Ge(001) substrate. At low temperature, the growth of nanowire domains is limited by the diffusion of Au. A wetting-dewetting transition occurs at a temperature of 665 K that transforms nanowire domains into three-dimensional Au clusters. Dewetting occurs at temperatures above 665 K and is fully reversible during repetitive heating and cooling cycles. The decay and growth rates of the nanowire domains below 665 K show intriguing dynamics, caused by the complex diffusion of gold. It correlates directly with the diffracted intensity of a reconstruction along the top of the nanowires, indicating a temperature-dependent potential landscape for the thermally activated diffusion of Au atoms across nanowire domains.