Quasiparticle energies and optical excitations of 3C-SiC divacancy from $GW$ and $GW$ plus Bethe-Salpeter equation calculations

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Quasiparticle energies and optical excitations of 3C-SiC divacancy from $G W$ and $G W$ plus Bethe-Salpeter equation calculations

Weiwei Gao, Felipe H. da Jornada, Mauro Del Ben, Jack Deslippe, Steven G. Louie, and James R. Chelikowsky

Phys. Rev. Materials 6, 036201 – Published 17 March 2022

Abstract

Excitons localized around point defects in semiconductors are promising candidates for long-lived and photon-addressable qubits. However, their microscopic origin is difficult to characterize due to the computational complexity of studying large systems with defects. Here we study the quasiparticle and optical absorption spectrum of the divacancy defect in 3C-SiC, a prototypical defect for quantum information applications, by means of large-scale $G W$ and $G W$ plus Bethe-Salpeter equation calculations. Despite the presence of localized unoccupied quasiparticle states in the gap, we find that the low-energy excitonic states are made primarily of transitions from occupied defect states to continuum conduction states from SiC, especially from the $X$ point of the Brillouin zone. The mixed character of defect states and bulk states of these low-energy exciton states is in contrast with the ${NV}^{-}$ center in diamond and the divacancy in 4H-SiC, where the deep defect levels are well separated from bulk states. Our calculations provide a quantitative prediction of the defect quasiparticle energy levels and a physical understanding of the zero-phonon absorption. They highlight the important role of frontier conduction bands in the optical properties and formation of low-energy excitons in 3C-SiC divacancy.

Received 20 December 2021
Accepted 16 February 2022

DOI:https://doi.org/10.1103/PhysRevMaterials.6.036201

Physics Subject Headings (PhySH)

Excitons Point defects Quantum information with solid state qubits Quasiparticles & collective excitations

Bethe-Salpeter equation Density functional theory GW method

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Weiwei Gao^1,2,*, Felipe H. da Jornada^3,4,5,*, Mauro Del Ben^6,*, Jack Deslippe⁷, Steven G. Louie ^4,5,†, and James R. Chelikowsky^1,8,9,‡

¹Center for Computational Materials, Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
²Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
³Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
⁴Department of Physics, University of California at Berkeley, California 94720, USA
⁵Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁶Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁷NERSC, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁸Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
⁹McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA