The annealing behavior of defects in n-type 6H SiC epilayers, irradiated with 2MeV electrons, was studied by using positron annihilation and deep-level transient spectroscopy. Vacancy-type defects were annealed out at 500 to 700C and at 1200 to 1400C. From an analysis of Doppler broadening spectra (core electron momentum distribution), the latter annealing process could be attributed to the disappearance of complexes that were related to Si vacancies and not to nearest-neighbor divacancies. Among the observed deep levels, the E1/E2 levels exhibited a similar annealing behavior to that of positron annihilation centers above 1000C. It was therefore proposed that the E1/E2 levels originated from complexes which contained Si vacancies.

Vacancies and Deep Levels in Electron-Irradiated 6H SiC Epilayers Studied by Positron Annihilation and Deep Level Transient Spectroscopy. A.Kawasuso, F.Redmann, R.Krause-Rehberg, T.Frank, M.Weidner, G.Pensl, P.Sperr, H.Itoh: Journal of Applied Physics, 2001, 90[7], 3377-82