Electron affinity of the bare and hydrogen covered single crystal diamond (111) surface

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