Monocrystals of N-doped (2 x 1018 to 3 x 1018/cm3) carbide, with an hexagonal structure (6H polytype), were grown by using a modified Lely technique. Positron lifetime studies were made of their atomic defects after irradiation (80K, 0.47 or 2.5MeV, 1.8 x 1017 to 1.9 x 1019/cm2) and after subsequent isochronal annealing at temperatures of up to 1900K. According to the positron lifetime measurements, very different types of vacancy-like positron traps were introduced by low-energy or high-energy irradiation. Defect agglomerates formed, and decayed during isochronal annealing at high temperatures.

A.A.Rempel, H.E.Schaefer: Applied Physics A, 1995, 61[1], 51-3