An investigation was made of the electrical and structural properties of Al- and B-implanted 4H-type material by using secondary ion mass spectroscopic, low-temperature photoluminescence, Hall-effect and positron annihilation spectroscopic techniques. In B-implanted samples, marked diffusion towards the interior or towards the surface was observed during post-annealing at 1700C. This was not observed in Al-implanted samples. A luminescence (427.2nm) which was independent of the dopant species and annealing temperature, and arose from the so-called D1 centre, was introduced by implantation and post-annealing. The positron lifetime (216ps) for both Al and B as-implanted samples was in good agreement with the theoretical lifetime (214ps) for a positron localized at a Si-C divacancy. The positron lifetimes of post-annealed samples (148, 147, 149ps) were between that of a virgin sample (144ps) and the theoretical lifetime (153ps) for a positron localized at a C vacancy. It was proposed that a defect such as a di-interstitial or a di-vacancy predominated in post-annealed samples.

Electrical and Structural Properties of Al and B Implanted 4H-SiC Y.Tanaka, N.Kobayashi, H.Okumura, R.Suzuki, T.Ohdaira, M.Hasegawa, M.Ogura, S.Yoshida, H.Tanoue: Materials Science Forum, 2000, 338-342, 909-12