Native defects in second-generation topological insulators: Effect of spin-orbit interaction on Bi2Se3

Abstract

Native defects in pnictogen chalcogenides are currently a great barrier toward the realization of the exotic properties of this class of topological insulators. Previous first-principles results of low-energy defects in Bi 2 Te 3 and Sb 2 Te 3 are in qualitative agreement with experiments. However, for Bi 2 Se 3 the calculated low-energy defects are antisites, opposed to Se vacancy (V Se) as observed experimentally. We find that the inclusion of spin-orbit interaction drastically shift the band-edge energies of the bulk states with respect to defect transition energies. It turns Bi antisite (Bi Se) from an acceptor to a donor and makes V Se more stable than Bi Se. This brings the calculated results for native defects in pnictogen chalcogenides into agreement with experiments.

First-principles calculation of intrinsic defect chemistry and self-doping in PbTe

“…1, the literature in thermoelectric materials often shows qualitatively different results. [14][15][16][17][18] Here, we consider PbTe a well studied material with strong spin-orbit coupling, to demonstrate the challenges posed in first-principles based density functional theory (DFT) calculations aimed at bulk properties, [19][20][21][22][23][24][25] and intrinsic defects. 14,15,[26][27][28] The DFT calculations employing the local density approximation (LDA) 29 or the generalized gradient approximation (GGA) 30 for exchange correlation provide only a qualitative description of the electronic structure of PbTe.…”

Stability, electronic, and magnetic properties of the magnetically doped topological insulatorsBi2Se3, Bi2TeZhang1, Ming2, Huang3 et al. 2013Phys. Rev. B

“…42,43 In particular, spin orbit coupling (SOC) is explicitly included due to the strong relativistic effect in Bi and Sb elements, and the significant impact on electronic structure and formation energy, 44 as also revealed by West et al 45 We choose hexagonal cell with the experimental lattice constants a=4.138Å, c=28.64Å for Bi 2 Se 3 ; a=4.383Å, c=30.487 A for Bi 2 Te 3 and a=4.250Å, c=30.35Å for Sb 2 Te 3 . The cutoff energy for the plane wave expansion of electron wavefunction was set at 300 eV.…”

Spin-polarized quantum well states onBi2−xFexSe3

“…The spatial separation of distinct impurities can be understood from calculations showing that Fe substitution in Bi 2 Se 3 is allowed only in Se-rich conditions [43,44], which also inhibit the formation of Se vacancies [45,46]. On the other hand, Fe interstitials are not energetically favored under any Bi/Se ratio.…”