Atomic and Electronic Structures of Co-Related Point Defects in CoSb3

Abstract

Co-vacancies (V Co ) and Co-interstitials (Co i ) have been suggested to play key roles in p-type doping in CoSb 3 under Sb-rich and Co-rich conditions, respectively. Based on density-functional theory calculations, we report detailed atomic and electronic structures of the Co-related point defects in CoSb 3 . The Co-vacancy is found to induce increases in the long and short bond lengths of the nearby Sb 4 rings, generating Sb 4 -p-like acceptor states inside the band gap. Co-interstitial is found to have a sevenfold coordination number in the lowest energy configuration, and gives a single 3d-like acceptor state slightly above the valence-band maximum. The sevenfold Co-interstitials can be paired with an additional Co i -Co i bond, and by the pairing, the 3d-like acceptor state becomes deep inside the band gap, and new donor states are found to emerge inside the band gap.

Effect of Native Defects on Transport Properties in Non-Stoichiometric CoSb3

“…Variations of non-stoichiometry in CoSb 3 can lead to either n -type or p -type conduction [ 19 , 20 ]. Sb-enriched samples have p -type conduction and Sb-deficient samples will lead to an excess of electrons in the conduction band, showing an n -type behavior [ 21 ].…”