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

Abstract

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 Al at a Si site. Both the B Si+H BC and the Al Si+H AB C 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.