Pulsed slow positron beam-based lifetime spectroscopy was used to investigate the nature of the acceptors and charge states of vacancy-type defects in low-energy proton-implanted 6H–SiC(H). It was deduced, from the temperature dependence of the lifetime spectra, that neutral and negatively charged vacancy clusters existed in the track region. Depending upon the annealing, they gave rise to positron lifetimes of 257, 281 and 345ps. The 281ps cluster probably had an ionization level near to the middle of the band-gap. By comparison with theory, the 257 and 280ps were identified as being (VC–VSi)2 and (VC–VSi)3 clusters, respectively. In addition, other acceptors of ionic type acted as strong trapping centers at low temperatures (less than 150K). Neutral monovacancy-like complexes were also detected, with a lifetime of 160ps after 900C annealing.

Negatively Charged Vacancy Defects in 6H–SiC after Low-Energy Proton Implantation and Annealing. M.F.Barthe, D.T.Britton, C.Corbel, A.Hempel, L.Henry, P.Desgardin, W.Bauer-Kugelmann, G.Kögel, P.Sperr, W.Triftshäuser: Physica B, 2001, 308-310, 668-70