Electronic structure of Humble defects in Ge and Ge0.8Si0.2

Shang Ren, Hongbin Yang, Sobhit Singh, Philip E. Batson, Eric L. Garfunkel, and David Vanderbilt
Phys. Rev. B 106, 155302 – Published 6 October 2022

Abstract

The group-IV diamond-structure elements are known to host a variety of planar defects, including {001} planar defects in C and {001}, {111}, and {113} planar defects in Si and Ge. Among the {001} planar defects, the Humble defect, known for some time to occur in Ge, has recently also been observed in Si-Ge alloys, but the details of its electronic structure remain poorly understood. Here we perform first-principles density-functional calculations to study Humble defects in both Ge and Ge0.8Si0.2. We also measure the Si L2,3-edge electron energy-loss spectra both at the defect and in a bulk-like region far from the defect and compare with theoretical calculations on corresponding Si sites in our first-principles calculations. We find that inclusion of core-hole effects in the theory is essential for reproducing the observed L2,3 edge spectra, and that once they are included, the results provide a set of fingerprints for different types of local atomic bonding environments in Ge0.8Si0.2. Our first-principles calculations reveal that the Humble defects have a tendency to enlarge the electronic band gap, which may have potential uses in band engineering. The use of hybrid functionals for an improved description of the band gap in these systems is also discussed.

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  • Received 27 June 2022
  • Accepted 13 September 2022

DOI:https://doi.org/10.1103/PhysRevB.106.155302

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shang Ren1,*, Hongbin Yang2, Sobhit Singh1,3, Philip E. Batson1, Eric L. Garfunkel2,1, and David Vanderbilt1

  • 1Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
  • 2Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
  • 3Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627, USA

  • *shangren@physics.rutgers.edu

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Vol. 106, Iss. 15 — 15 October 2022

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