Changes in the Au coverage and structure, of the (111) v3 x v3 surface, which were induced by isothermal annealing at temperatures ranging from 500 to 575C, were monitored by using low-energy electron diffraction, Auger electron spectroscopy, and Rutherford back-scattering spectrometry. It was found that the Au coverages which were determined at each temperature decreased exponentially to 0.75 of a monolayer. Above this, only a low-energy diffraction pattern of v3 x v3 spots was observed. A mixture of v3 x v3 and 5 x 1 spots was observed at coverages down to 0.54 of a monolayer (575C), 0.52 of a monolayer (550C), or 0.61 of a monolayer (530C). Below these limits, only the low-energy electron diffraction pattern of 5 x 1 spots was observed. By analyzing the decay curves of the Au coverages, it was deduced that the activation energies required for Au atoms to move from the v3 x v3 or the 5 x 1 structure and into the bulk were 2.5 and 2.8eV, respectively. The activation energy required for a phase transition of the Au/(001)Si surface, from the v3 x v3 to the 5 x 1 structure, was 1.6eV.

J.Yuhara, M.Inoue, K.Morita: Journal of Vacuum Science and Technology A, 1992, 10[2], 334-9