Reflectance anisotropic spectroscopy was used to investigate As desorption from (001) surfaces at various temperatures. The highest As coverage, which was found at low temperatures under arsine stabilization, corresponded to a (4 x 3) reconstruction. In the absence of arsine, the As began to desorb and less As-rich reconstructions were observed; depending upon the temperature. That is: c(4 x 4) below 800K, β2(2 x 4) below 920K, and a(2 x 4). Only under H carrier gas did (4 x 2) finally appear, above 950K. At temperatures above 920K, the order of reaction differed in H and N atmosphere. This was thought to be due to an etching effect of H radicals. The 5 different desorption processes exhibited either a first- or zero-order time dependence. The first-order dependence was related to desorption from the terraces, and the zero order dependence was related to desorption from steps or kinks on the surfaces. The activation energies for all of the processes were about 2.5eV. This energy was assumed to be the activation energy for the removal of an As dimer from the surface.

Dynamic Study of the Surfaces of (001) Gallium Arsenide in Metal-Organic Vapor-Phase Epitaxy during Arsenic Desorption M.Pristovsek, T.Trepk, M.Klein, J.T.Zettler, W.Richter: Journal of Applied Physics, 2000, 87[3], 1245-50