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Published online by Cambridge University Press: 17 March 2011
A brief survey of some of the recent results of recombination-induced defect reactions involving hydrogen in 4H and 6H-SiC is given. A variety of outcomes of such reactions have been observed in hydrogenated 4H and 6H-SiC polytypes under optical excitation at reduced temperature. A few different non-metastable hydrogen-defect complexes can form, including hydrogen complexes with Al and B acceptors, hydrogen complex with Si vacancy, as well as some other non-identified complexes. Electrical measurements indicated strong recombination-induced passivation of the electrical activity of aluminum and boron acceptors in SiC. This passivation resulted in the reduction of the net free hole concentration and even inversion of the conductivity type. It is suggested that optical excitation causes a long-range migration of hydrogen followed by its capture in one or another kind of defect complexes. Further insight in the formation of specific complexes as a result of recombination-induced defect reactions is provided by thermal admittance spectroscopy. Energy gap levels in the regions that remained p-type after hydrogenation as well as in the regions where the conductivity was inverted by the recombination-induced passivation are investigated.