Molecule oxygen-driven shaping of gold islands under thermal annealing

Fabrication of the gold micro/nano-structure in a controlled manner has recently attracted considerable interest for its potential applications. With the help of the AFM and XRD measurements, our research on the annealing of the evaporated thin gold films under different thermal environments reveals that O2 molecule, of which the influence has been generally ignored in the prevenient literatures, can play a very important role in the formation of gold island film. It is experimentally found that the molecule oxygen-driven migration of gold atoms can only occur at a high enough temperature. The time-dependent morphological development of the thin gold film annealing in O2 is also observed, which is determined by the reduction of the whole interface energy. The morphological features of the Au islands, such as the flat top surfaces and the steep edges, point to the essential role of the interaction between oxygen and the specifically oriented gold surface during the structural evolution.