Intrinsic point defects and the n- and p-type dopability of the narrow gap semiconductors GaSb and InSb

The presence of defects in the narrow-gap semiconductors GaSb and InSb\naffects their dopability and hence applicability for a range of optoelectronic\napplications. Here, we report hybrid density functional theory based\ncalculations of the properties of intrinsic point defects in the two systems,\nincluding spin orbit coupling effects, which influence strongly their band\nstructures. With the hybrid DFT approach we adopt, we obtain excellent\nagreement between our calculated band dispersions, structural, elastic and\nvibrational properties and available measurements. We compute point defect\nformation energies in both systems, finding that antisite disorder tends to\ndominate, apart from in GaSb under certain conditions, where cation vacancies\ncan form in significant concentrations. Calculated self-consistent Fermi\nenergies and equilibrium carrier and defect concentrations confirm the\nintrinsic $n$- and $p$-type behaviour of both materials under anion-rich and\nanion-poor conditions. Moreover, by computing the compensating defect\nconcentrations due to the presence of ionised donors and acceptors, we explain\nthe observed dopability of GaSb and InSb.\n