SCANNING-TUNNELING-MICROSCOPY AND SPECTROSCOPY SIMULATION OF THE GAAS(110) SURFACE

We have generated, using an ab initio pseudopotential method and the Bardeen transfer Hamiltonian approximation, scanning-tunneling- microscopy images and scanning-tunneling-spectroscopy spectra of the GaAs(110) surface. The surface was fully relaxed and a cluster of four Al atoms was used to represent the tip. We investigate the effect of different tip-surface bias voltages on the scanning-tunneling microscopy images and compare them to experimental results. In particular, the effectiveness of using the images to determine the buckling angle of the surface bond is discussed. For the scanning-tunneling-spectroscopy spectra, different lateral tip positions were utilized and various features associated with surface states were identified, which we also compare with experiment.