Direct observation of GaP(110) surface states

Abstract
We report the direct observation of the dangling-bond surface state in gallium phosphide. A strong surface-sensitive feature is detected at -0.8±0.05 eV from the top of the valence band. The results, obtained by synchrotron radiation angle-integrated photoemission, are in agreement with the predictions of a theoretical model based on a 27.5° rotation of the Ga-P bond. The analysis of the data indicates that the phosphorus site is likely the oxygen chemisorption site at the initial stages of exposure.