LINE BROADENING IN SEMICONDUCTOR CORE-LEVEL PHOTOEMISSION INDUCED BY BARRIER HEIGHT INHOMOGENEITY

High resolution core level photoemission spectra from clean GaAs(110) semiconductor surfaces are analyzed considering the possibility of focal barrier height variations at the surface. A simple model calculation is presented and is used to predict the effects of such local variations on the line shape of Ga 3d and As 3d core level emission. We clearly show that the presence of differently pinned zones on the surface leads to an extra broadening which may mask some of the important information usually extracted by conventional core level fitting analysis. By discussing the Ga 3d and As 3d line shape changes, which occur as a function of temperature, we give experimental evidence that barrier height fluctuations can indeed be present and can strongly affect core level photoemission spectra.