Synthetic boron-doped single-crystal diamonds were irradiated by a pulsed electron beam at 2.2MeV to various accumulated fluences from 0.7 x 1018 to 10 x 1018e−cm−2. The samples were then subjected to isochronal annealing up to 1260 C and characterized by positron annihilation and optical absorption spectroscopy after each annealing step. Positron annihilation, combined with in situ monochromatic illumination, gave an estimate for the positive/neutral energy level in the band gap for the monovacancy as ~0.6eV above the valence band-edge. From the analysis of positron annihilation and optical absorption results, a dominant optical absorption line at 0.552eV was associated with a neutral boron–interstitial complex, and the annealing temperature of the positive monovacancy was deduced to be ~700C.

Defects in Electron Irradiated Boron-Doped Diamonds Investigated by Positron Annihilation and Optical Absorption. S.Dannefaer, K.Iakoubovskii: Journal of Physics - Condensed Matter, 2008, 20[23], 235225