First-principles local density approximation calculations were carried out for dopant-related complexes. Cluster models, with localized basis functions, were used to calculate spin distributions while super-cell calculations were used to determine the relative stabilities as a function of the chemical potential. It was shown that a divacancy which captured a P atom gave rise to a deep donor level. On the basis of the calculated spin distribution on a P atom in the Si site next to a C vacancy, (PSi + VC), such a complex could be identified with the so-called P-V electron paramagnetic resonance centre. It was shown that, at high Si/C ratios, the formation energies of P at the C site (PC) and at the Si site were about the same in thermal equilibrium. The PC was also an effective mass donor in 3C-type material. It was established that substituted B chose the Si site in a divacancy, in both the neutral and negative charge states. That is, no bistability occurred. The resultant BSi + VC complex was a deep acceptor with a spin distribution which was very close to that measured by using ENDOR techniques. However, the acceptor part of the complex was VC, and this explained why the photoluminescence spectra indicated that the acceptor was on the same sub-lattice as NC.

Dopant-Related Complexes in SiC. A.Gali, J.Miró, P.Deák, R.P.Devaty, W.J.Choyke: Materials Science Forum, 2000, 338-342, 795-8