HIGH-RESOLUTION SURFACE-SENSITIVE C-1S CORE-LEVEL SPECTRA OF CLEAN AND HYDROGEN-TERMINATED DIAMOND(100) AND DIAMOND(111) SURFACES

The carbon 1s core levels of diamond (100) and (111) surfaces were inv estigated using high-resolution photoelectron spectroscopy. The Surfac es were prepared ina hydrogen plasma, which is known to result in atom ically flat surfaces. From the signature of the C 1s core-level spectr a, four different surface terminations can be distinguished. The as-pr epared surfaces exhibit a surface component shifted by +0.5 to +0.8 eV toward higher binding energy, which we assign to multiple termination of carbon atoms by hydrogen. Annealing these surfaces first results i n the development of the surfaces terminated monoatomically by hydroge n. A small chemical shift of -0.15 eV was deduced for the hydrogen-ter minated surface atoms of the (111):H surface with respect to the bulk carbon atoms. Further annealing leads to spectra characteristic for hy drogen-free, reconstructed diamond surfaces. This process is shown to be thermally activated with an activation energy of 3.4+/-0.4 eV. The corresponding chemical shifts between surface and bulk components vary between -0.78 and -1.15 eV depending on surface orientation and surfa ce treatment. Finally, annealing at T approximate to 1250 degrees C le ads to a partially graphitized surface for diamond (111) while on the diamond (100) surface a 4x1 reconstruction is observed. The sign and m agnitudes of the chemical shifts are discussed. [S0163-1829(98)11119-0 ].