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Abstract We report positron annihilation results on in-grown and proton-irradiation-induced vacancy defects in AlN single crystals grown by physical vapor transport. The samples were irradiated with 100 keV H + ions to varying fluences in the range of 5 × 10 14 − 2 × 10 18 ions cm –2 . Doppler broadening of annihilation radiation was recorded in as-grown and irradiated samples with a slow positron beam with varying implantation energy. Doppler results combined with first principles theoretical calculations show that the 100 keV H + irradiation introduces isolated V Al on the ion track and V N -rich vacancy clusters at the end of the ion range. The results suggest that the excess amount of detected V N originates from a high concentration of in-grown V N . So far, these defects have been considered to be unidentified negative ion-like defects in AlN.
Prozheev et al. (Fri,) studied this question.