ISSN - 00396028, Surface Science, 2002, vol. 507-510, p. 411-416
Local-order of chemically-prepared GaAs(1 0 0) surfaces
In the present work HCl-propanol treated and vacuum annealed GaAs(1 0 0) surfaces were studied by means of soft X-ray photoemission and reflectance anisotropy spectroscopies (SXPS, RAS). On the as-treated surface, As3d and Ga3d core level spectra (CLs) are found to be similar to the ones observed on As-capped GaAs(1 0 0) surfaces after annealing at 350 °C, which desorbs most of the overlayer. RAS measurements of the as-treated surface and after annealing up to 350 °C show spectra similar to those detected on the as-grown surfaces with c(4 × 4) reconstruction. Anneals in the 380-470 °C temperature range lead to the appearance of a RAS line at 3 eV which is characteristic of As dimers. This finding coincides with the presence of a surface component in the As3d core level spectrum with a chemical shift of -0.5 eV, which we attribute to As-dimers. Further annealing at 540 °C yields in RAS spectra an intense line at 2.2 eV due to Ga dimers, while the Ga3d CLs do not exhibit any appreciable change. © 2002 Elsevier Science B.V. All rights reserved.