The Ar and C ion bombardment of p-type samples at 500 to 5000eV in ultra-high vacuum were studied by means of  in situ  X-ray photo-electron spectroscopy and low-energy electron diffraction techniques. Both types of ion bombardment created a defective surface layer at room temperature. The presence of radiation damage was indicated by the introduction of a distinct C 1s peak with a binding energy which was about 1eV less than that of the peak for bulk material. It was also revealed by the introduction of additional filled states which were near to the valence band edge. It was noted that, in comparison with Ar bombardment, C bombardment was more efficient in producing filled states but less efficient in increasing the C 1s defect peak. Although the filled states disappeared during annealing at about 500C, the C 1s defect peak did not change much; even during annealing at 1000C. It was suggested that the C 1s defect peak (which had also been observed on reconstructed diamond surfaces after H desorption) was associated with vacancy formation and aggregation which produced so-called internal surfaces which behaved like reconstructed atomically clean diamond surfaces. The filled states which were introduced by ion bombardment were associated with interstitials or interstitial clusters. The number of residual defects was found to increase with increasing bombardment dose and energy.

W.M.Lau, L.J.Huang, I.Bello, Y.M.Yiu, S.T.Lee: Journal of Applied Physics, 1994, 75[7], 3385-91