It was found that Ga-terminated (4 x 2) surface reconstructions could be obtained on clean GaAs substrates by using a completely dry process, at temperatures below the oxide sublimation temperature, and without a group-V element over-pressure. The native oxides were removed by using an electron cyclotron resonance H plasma treatment, followed by annealing at 500C in ultra-high vacuum. This produced a reconstructed surface which was suitable for epitaxial over-growth. Characterization, by means of secondary ion mass spectroscopy and transmission electron microscopy, revealed the complete removal of O, reduced C, and high structural order at the epilayer/substrate interface when this preparation method was used before molecular beam epitaxy. Annealing of the substrate at a lower temperature yielded a non-reconstructed surface which contained a significant impurity concentration, and produced dislocation defects at the epilayer/substrate interface.

K.D.Choquette, M.Hong, H.S.Luftman, S.N.G.Chu, J.P.Mannaerts, R.C.Wetzel, R.S.Freund: Journal of Applied Physics, 1993, 73[4], 2035-7