The annealing of defects in proton-irradiated bulk 6H- and 4H-polytypes was investigated by means of positron lifetime spectroscopic and Doppler-broadening measurements. Experiments were performed on N-doped (n-type) or Al-doped (p-type) crystals. In n-type material, the radiation-induced defects annealed out in 4 stages at 150, 350, 750 and above 1000C. The magnitudes of the annealing stages depended upon the proton fluence. In p-type material, the increase in the positron parameters after irradiation was smaller and a differing annealing behaviour was observed after the first annealing stage at about 150C. Semi-insulating samples did not exhibit the annealing stage at 1000C.

Vacancy-Type Defects in Proton-Irradiated 6H- and 4H-SiC - a Systematic Study with Positron Annihilation Techniques. W.Puff, A.G.Balogh, P.Mascher: Materials Science Forum, 2000, 338-342, 969-72