The surface reconstruction of (100) AlAs layers which had been grown, by means of molecular beam epitaxy, onto (100) GaAs substrates was studied as a function of substrate temperature and As flux. Three main reconstructions were observed. These were c(4 x 4) at lower temperatures and higher As fluxes, (2 x 4) at moderate temperatures, and (3 x 2) at higher temperatures and lower As fluxes. The growth of AlAs onto (100) AlAs was of layer-by-layer type for both high- and low temperature reconstructions. In the intermediate temperature range, the AlAs grew in a rough manner on (2 x 4) reconstructed (100) AlAs; as indicated by rapidly damped reflection high-energy electron diffraction intensity oscillations and by the appearance of 3-dimensional features. The addition of fractional layers of Ga enhanced the smooth growth of AlAs. A metastable (5 x 2) reconstruction was observed when a fraction of a layer of Ga was present on the surface. The results indicated that Ga segregated, during the growth of AlAs on (100) GaAs, at temperatures down to at least 500C. Also, annealing at temperatures above 700C removed most of the Ga from the surface.

A.M.Dabiran, P.I.Cohen: Journal of Crystal Growth, 1995, 150[1-4], 23-7