Reflection high-energy electron diffraction measurements were performed during the molecular beam epitaxial growth of GaAs and InGaAs on GaAs(111)A and (111)B surfaces. Under a given Ga flux, the period of these intensity oscillations increased with increasing As4 flux on the 2 x 2 reconstructed GaAs(111)B surfaces. Layer thickness measurements, made using cross-sectional transmission electron microscopy of AlAs/GaAs superlattices, indicated that the real growth rate did not correspond to the measured period of the intensity oscillations. The results were explained in terms of a reduction in Ga incorporation, and an enhancement of Ga surface diffusion as the As coverage of the 2 x 2 reconstructed (111)B surfaces was increased. The reduced Ga incorporation, on GaAs(111)B, promoted the formation of facets which were commonly observed as 3-dimensional islands or hillocks, which intercepted a portion of the Ga flux. Molecular beam epitaxial growth and relaxation of strained InGaAs layers on GaAs(111)B were also studied by means of reflection high-energy electron diffraction intensity oscillations and in situ surface lattice constant measurements. It was shown that, by fine-tuning the molecular beam epitaxial parameters during the growth of GaAs buffers and InGaAs layers on GaAs(111)B, premature strain relaxation due to the formation of twin defects could be prevented. Unlike the case of growth of InGaAs on GaAs(100), no 2-dimensional to 3-dimensional transition was observed; even at high strains.

A.M.Dabiran, P.I.Cohen, J.E.Angelo, W.W.Gerberich: Thin Solid Films, 1993, 231[1-2], 1-7