Absence of long-range ordered reconstruction on the GaAs„311...A surface

We have investigated the decapped GaAs~311!A surface using both scanning tunneling microscopy and synchrotron-radiation photoemission. While our data are in broad agreement with the structural model of GaAs~311!A proposed in a recent study @Wassermeier et al., Phys. Rev. B 51, 14 721 ~1995!#, we find considerable differences in the surface order. In particular, the As dimer rows are unbroken over much shorter length scales and are highly kinked. We observe a correspondingly lower degree of anisotropy in the surface roughness than that previously reported. An (831) reconstruction was not observed. An analysis of As 3d and Ga 3d core-level photoemission spectra suggests that surface As atoms are in only one bonding configuration while surface Ga adopts two different bonding states. We discuss possible origins for the core-level spectra surface components. @S0163-1829~97!01420-3#