Dielectric function and electronic structure of nondegenerate rocksalt ScN: Spectroscopic ellipsometry and                    <math>                      <mrow>                        <mi>GW</mi>                      </mrow>                    </math>                    calculations

Jona Grümbel; Rüdiger Goldhahn; Martin Feneberg; Yuichi Oshima; Hazem Abu-Farsakh; Abdallah Qteish

doi:10.1103/3fxb-cd53

Journal article Dielectric function and electronic structure of nondegenerate rocksalt ScN: Spectroscopic ellipsometry and $GW$ calculations

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Jona Grümbel, Rüdiger Goldhahn, Martin Feneberg, Yuichi Oshima, Hazem Abu-Farsakh, Abdallah Qteish. Dielectric function and electronic structure of nondegenerate rocksalt ScN: Spectroscopic ellipsometry and

GW

calculations. Physical Review Materials. 2026, 10 (2), 024607. https://doi.org/10.1103/3fxb-cd53

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In this work, we determine the dielectric function of ScN in a spectral range from 0.9 to 6.4 eV by spectroscopic ellipsometry from nondegenerate doped, bulk-like samples. Several models are applied to the obtained dielectric functions yielding the main critical-point transition energies. These results are compared with state-of-the-art computations, where the band structure of ScN is calculated using Heyd-Scuseria-Ernzerhof (HSE06) hybrid functionals and quasiparticle corrections in the G0W0 approach. Furthermore, the dielectric function of ScN is derived from the computed band structure by solving the Bethe-Salpeter equation to account for electron-hole-pair interactions. We find exceptional agreement between computed and experimentally determined dielectric functions, where discrete excitons are not observed experimentally. We extrapolate an intrinsic direct band gap of (2.182 ± 0.004) eV and an intrinsic indirect band gap of (1.08 ± 0.02 eV) by taking into account many-body effects, while higher energy critical-point transition energies of Γ-point transitions are averaged over all samples, yielding E = (3.853 ± 0.006) eV and E = (5.21 ± 0.02) eV. Critical-point transitions in the computed band structure, although, deviate from the experimental ones due to the omission of electron-hole-interaction, where the deviation increases with increasing energy. The dielectric limit of the electronic system is determined as ε∞ = 8.38 ± 0.04 from experiment, where the computed dielectric function reveals almost the same value (ε∞ = 8.33). Along with other previous publications, we conclude that solving the Bethe-Salpeter equation is indispensable for the computation of the dielectric function of semiconductors even in the absence of discrete excitons.

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