Recovery kinetics of the GaAs(0Â 0Â 1) surface in molecular beam epitaxy studied by in situ X-ray diffraction

Grazing incidence X-ray diffraction is used to study the GaAs(0 0 1) surface kinetics after a fractional number of monolayers is deposited by molecular beam epitaxy. We compare submonolayer depositions with the growth of non-integer number of layers. The coarsening exponent n of the mean 2D island size, l(t)∼tn, is found to be n=0.93±0.18. This exponent is notably larger than the Lifshitz-Slyozov exponent n=1/3 expected for Ostwald ripening. A possible origin of this difference is discussed.