Self-limiting cyclic growth of gallium droplets on Si(111)

In this paper the growth of Ga droplets on a vicinal Si(111) surface is discussed. We report that the droplet size can be controlled down to the sub-100 nm range by carefully chosen deposition conditions. In addition, the dependence of the droplet size on deposition time is not monotonic, but shows self-limiting behaviour: with increasing amount of Ga on the surface the droplets stop increasing in lateral dimension and, instead, additional droplets of the same size are formed on the surface. Further, in the case of deposition at 300 deg. C substrate temperature it has been found that the growth proceeds in cycles. Thus, not only the size but also the droplet concentration can be controlled. In this way, non-ordered arrays of metallic droplets with a very narrow size distribution can be grown.