Passivation of p-type dopants in 4H-SiC by hydrogen

Experimental investigations showed passivation of the p-type dopants B and Al in 4H-SiC by the formation of B + H and Al + H complexes. The dissociation energies of these complexes differed by 0.9 eV. Ab initio supercell calculations have been performed to investigate the interaction of H with B and Al in hexagonal 4H-SiC. The total energy, geometry and electronic structure of the possible complexes have been determined. Site dependencies have also been investigated. The most stable configurations were found with H at a bond center site next to B at the Si site, and with H at the antibonding site of a carbon atom which is first neighbor to A] at a Si site. Both the B-si + H-BC and the Al-si + H-ABc complexes turned out to be electrically inactive. The different structure of the passivated complexes explains the observed difference in their dissociation energy: the calculated difference of the binding energies of these complexes is 0.9 eV, which agrees well with the experimental finding. (C) 2001 Elsevier Science B.V. All rights reserved.