Gallium-rich reconstructions on GaAs(001)

摘要

Ga-rich reconstructions on GaAs(001) surfaces were prepared by annealing and Ga dosing of Molecular Beam Epitaxy grown samples and analyzed in-situ by Reflectance Anisotropy Spectroscopy and Reflection High-Energy Electron Diffraction. Annealing or dosing gallium above about 900 K invariably results in a (4 x 2)/c(8 x 2) reconstruction. Lowering the temperature or annealing below 800 K results in a (2 x 6)/(3 x 6) reconstruction. By dosing the (2 x 6)/(3 x 6) reconstruction with more than 0.2 monolayer of gallium, it transforms into a (4 x 6) reconstruction. The observed translational symmetries and measured RAS spectra are compared with results of first-principles calculations. None of the (2 x 6) structures proposed in the literature is energetically stable. The RAS spectrum calculated for the (4 x 2) model resembles reasonably the data measured for the (4 x 2) surface. The RAS spectra calculated for (2 x 6) symmetries indicate that mixed Ga-As dimers likely are a structural element of the corresponding surface reconstructions. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. [References: 37]