Local structure analysis of heavily boron-doped diamond by soft x-ray spectroscopy

To clarify the electronic structure of metallic heavily boron (B)-doped diamonds, the discrete variational (DV)-X alpha method was used to analyze the continuous X-ray absorption near edge structure (XANES) in the BK and CK regions of a 71,000-ppm B-doped diamond. The continuous XANES profiles are well reproduced by the unoccupied B2p- and C2p-DOS of the caged B-cluster models, in which an octahedron B-6 cluster, a cuboctahedron B-12 cluster, or an icosahedron B-12 cluster is inserted into the defect space of the diamond lattice. The delocalized conduction band structure can be understood from the hybridization of the B atoms in B-clusters with the surrounding C atoms in the diamond lattice. The results indicate that the B atoms in heavily B-doped diamonds form caged B-clusters in the defect space of the diamond lattice. (C) 2013 Elsevier B.V. All rights reserved.