Non-Ostwald coarsening of the GaAs(001) surface

Abstract

We study the coarsening kinetics of the two-dimensional island/pit morphology on the GaAs(100) surface after deposition of a fractional layer using grazing incidence x-ray diffraction. We find that the correlation length $l(t)$ increases as $l(t)\ensuremath{\propto}{t}^{n},$ with n in the range 0.7--1.3. For spinodal decomposition (coverage 0.5), we observe linear recovery. Our observations do not fall into the known universality classes of conserved coarsening kinetics, the Lifshitz-Slyozov diffusion-limited kinetics $(l\ensuremath{\propto}{t}^{1/3}),$ or the Wagner attachment-limited kinetics $(l\ensuremath{\propto}{t}^{1/2}),$ and therefore cannot be explained by Ostwald ripening. We present experimental results on the coverage, temperature, and orientation dependence of the coarsening rate.