Transitions between (2 x 4)/c(2 x 8) and c(4 x 4) on (001) surfaces were studied by means of ultra-high vacuum scanning tunnelling microscopy. It was evident that Ga diffusion was appreciable, for distances of up to a micrometer, at the beginning of the transitions. However, diffusion was prevented by nucleation in the final stage of the transition. It was found that the size of the minimum nucleus depended upon reconstruction.

K.Kanisawa, H.Yamaguchi: Physical Review B, 1997, 56[19], 12080-3