Scanning Kelvin-probe study of the hydrogen-terminated diamond surface in ultrahigh vacuum

Atomic-force and Kelvin-probe microscopies were employed in ultrahigh vacuum to image the surface topography and contact potential of the hydrogen-terminated and unterminated surfaces of diamond. A variation of about 25 meV in the contact potential was measured on a length scale of 20 nm and ascribed to differently orientated surface domains resulting from hydrogen-plasma processing of the sample. Shifts in the work function arising from sample heating in vacuum and the adsorption of C(60) were measured. The Fermi level was found to be 0.7 and 1.1 eV below the valence band maximum for C(60) coverages of 1 and 4 monolayer, respectively. (C) 2009 American Institute of Physics. [doi:10.1063/1.3222864]