Gold diffusion into silicon at room temperature was observed in real time at atomic resolution. Gold nanoclusters were formed on a silicon surface by electrical discharges between a silicon tip and a gold-coated tip within an ultra-high vacuum transmission electron microscope specimen chamber. At the moment of gold nanocluster deposition, the nanoclusters had a crystalline structure. This gradually disappeared, due to the interdiffusion between silicon and gold after deposition of the gold nanoclusters. The shape of the nanocluster gradually changed due to gold diffusion into the damaged silicon. The diffusion front between silicon and gold moved towards the silicon side. From observations of the diffusion front, the gold diffusivity at room temperature was deduced. The activation energy of 0.21eV matched the activation energy for bulk diffusion between damaged silicon and gold.

Real-Time Transmission Electron Microscope Observation of Gold Nanoclusters Diffusing into Silicon at Room Temperature. T.Ishida, Y.Nakajima, J.Endo, D.Collard, H.Fujita: Nanotechnology, 2009, 20[6], 065705