Scaling of Island Size Distributions in the Growth of Ni on GaAs(110)

Abstract

ABSTRACTIsland size distributions have been derived from scanning tunneling microscope (STM) images of Ni deposited on cleaved GaAs(110) at room temperature and above. For submonolayer coverages, this system forms 3-dimensional (3-D) reacted islands with the degree of reaction dependent upon the growth temperature. As has been found for other systems, the average island size (sαυ) increases with temperature. The high temperature data (∼ 150° C) shows two distinct island types, each with substantially different average size. The island size distributions have maxima at the smallest island sizes. For different coverages, plots of the area-normalized island size distributions versus the scaled variable s/sαυ show significant differences. However, above a cutoff value for s/sαυ the distributions can be renormalized to fall on a common curve. These characteristics and direct atomic-scale evidence are consistent with nucleation of islands via adatom-substrate exchange, but the temperature dependence of the total island density appears to be inconsistent with this being the only first-order rate process taking place.