ELECTRON-AFFINITY OF THE BARE AND HYDROGEN COVERED SINGLE-CRYSTAL DIAMOND(111) SURFACE

The electron affinity chi and the band diagram of single crystal diamo nd (111) surfaces was determined as a function of hydrogen coverage by combining work function measurements with photoelectron yield and cor e level photoemission spectroscopy. chi ranges from -1.27 eV for the f ully hydrogen covered (1 X 1) surface to +0.38 eV for the hydrogen fre e (2 X 1) reconstructed surface. This change is quantitatively explain ed by a surface dipole model provided a coverage dependent depolarizat ion is included. The dipole moment of the C-H bond on diamond (111) is found to be 0.09 e Angstrom.