Gallium-terminated (4 x 2) surface reconstruction on virgin GaAs substrates was obtained by using a completely dry process at temperatures below the oxide sublimation temperature and without a group-V over-pressure. The native oxides were removed with an electron cyclotron resonance hydrogen plasma treatment, followed by annealing at 500C in ultra-high vacuum, which yields a reconstructed surface suitable for epitaxial overgrowth. Characterization by secondary ion mass spectroscopy and transmission electron microscopy reveals 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 the substrate at a lower temperature yields a non-reconstructed surface possessing significant impurity concentrations, and led to dislocation defects at the epilayer/substrate interface.

GaAs Surface Reconstruction Obtained using a Dry Process. 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