The surface dipole contribution to the work function for Sb on GaAs(110): a comparative study by Kelvin probe and Raman spectroscopy

Abstract

The adsorption of Sb on GaAs(110) at room temperature (RT) and liquid nitrogen temperature (LT) was studied in ultrahigh vacuum (UHV) by contact potential difference (CPD) measurements and by electric field induced Raman scattering (EFIRS) to monitor the changes in the work function and the band bending at the interface, respectively. By comparison, the surface dipole contribution to the changes in the work function was determined and correlated to the growth mode of the Sb.For RT deposition up to 1ML of Sb the work-function changes follow the development of the band bending at the interface, thus, no dipole contributions to the changes in work function are observed. For LT deposition, however, a surface dipole contributes to the observed work-function changes in addition to the band bending. The dipole contribution at LT can be explained by the distinct adsorption mode of the Sb: At LT the Sb atoms adsorb on random sites in contrast to the formation of an epitaxial monolayer at RT.