Samples of 4H- and 6H-type material were irradiated using various neutron fluences and energy distributions. The samples were then annealed at between 600 and 1850C, and characterized using Fourier-transform infra-red spectroscopy, low-temperature photoluminescence, Hall-effect, I-V, and C-V techniques. It was shown that fast neutrons produced most defects and that samples which were irradiated with similar thermal fluences exhibited approximately the same behaviour, after annealing at 1500 to 1650C, as did as-grown samples. Variation of the fast-neutron fraction by a factor of 9.4 x 104 showed that even a fraction of 1% of fast neutrons dominated defect generation. A fast-neutron fraction of about 10-4 produced samples which exhibited an almost as-grown behaviour. It was pointed out that most annealing processes destroyed the sample surface and, at higher temperatures, additional defects were generated. Doping with thermal neutrons was not expected to degrade device properties. Different annealing behaviours of p-type and n-type samples after similar irradiations were attributed to changes in Fermi level during annealing. It was nevertheless concluded that the annealing behaviour varied with the polytype and dopant-type.

Radiation Defects and Doping of SiC with Phosphorus by Nuclear Transmutation Doping. H.Heissenstein, H.Sadowski, C.Peppermüller, R.Helbig: Materials Science Forum, 2000, 338-342, 853-6