VALENCE-BAND SPECTROSCOPY OF RECONSTRUCTED (100) AND (111) NATURAL DIAMOND

The electronic structures of natural diamond type IIb single crystals of orientations (100) and (111) were investigated by core level and valence band photoelectron spectroscopy. The samples were measured at room temperature, and then heated in situ up to 955 degrees C. On annealing, a distinct decrease in oxygen contamination at the surface was observed; simultaneously additional electronic states near the valence band maxima appeared. These additional states can be interpreted as surface states of the reconstructed diamond (in both the (100) and (111) orientations). The data obtained are compared with other carbon phases, such as graphite and diamond films prepared by chemical vapour deposition.