Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Electronic band structure, band-to-band transitions, and anisotropic dielectric functions of orthorhombic NdGaO3

Traouli, Yousra ; Kilic, Ufuk ; Korlacki, Rafał ; Hilfiker, Matthew ; Mock, Alyssa ; Schubert, Eva and Schubert, Mathias LU orcid (2026) In Journal of Applied Physics 139(13).
Abstract

A set of ultrawide bandgap single-crystal NdGaO3 samples cut with crystallographic surface orientations (001), (101), and (110) are investigated by using generalized spectroscopic ellipsometry. We report the complex anisotropic dielectric functions in the spectral range from 0.73 to 9.0 eV, for polarization along directions a, b, and c of the orthorhombic unit cell. A Kramers–Kronig consistent parameterized model was utilized to identify critical point structures and their association with band-to-band transitions, and the results from density functional theory (DFT) calculations for the electronic band structure of NdGaO3 are compared. A Cauchy parameter analysis for the three refractive indices is performed in the below... (More)

A set of ultrawide bandgap single-crystal NdGaO3 samples cut with crystallographic surface orientations (001), (101), and (110) are investigated by using generalized spectroscopic ellipsometry. We report the complex anisotropic dielectric functions in the spectral range from 0.73 to 9.0 eV, for polarization along directions a, b, and c of the orthorhombic unit cell. A Kramers–Kronig consistent parameterized model was utilized to identify critical point structures and their association with band-to-band transitions, and the results from density functional theory (DFT) calculations for the electronic band structure of NdGaO3 are compared. A Cauchy parameter analysis for the three refractive indices is performed in the below bandgap spectral range. Dielectric functions along lattice directions a, b, and c and their respective bandgap energy values are very similar. Below the bandgap energy, the refractive index differences for directions a and b are very small (0.34% on average) while index differences with direction c (approximately 1.25%) lead to effective positive uniaxial optical properties (n c > n a ≈ n b) toward the phonon modes spectral range. Our ellipsometry analysis determines the lowest band-to-band transitions of NdGaO3 to occur at E a = 6.46 (6) eV, E b = 6.29 (5) eV, and E c = 6.77 (7) eV, i.e., E c > E a > E b, while our DFT calculations predict the first transition to be lowest along the a axis. We discuss our findings in light of previous reports and present all parameters of our theoretical and experimental analyses.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Applied Physics
volume
139
issue
13
article number
135703
publisher
American Institute of Physics (AIP)
external identifiers
  • scopus:105036223462
ISSN
0021-8979
DOI
10.1063/5.0320451
language
English
LU publication?
yes
id
556ddbf4-6669-4f7c-8dda-3af3a02f36a3
date added to LUP
2026-05-27 14:57:16
date last changed
2026-05-27 14:58:15
@article{556ddbf4-6669-4f7c-8dda-3af3a02f36a3,
  abstract     = {{<p>A set of ultrawide bandgap single-crystal NdGaO3 samples cut with crystallographic surface orientations (001), (101), and (110) are investigated by using generalized spectroscopic ellipsometry. We report the complex anisotropic dielectric functions in the spectral range from 0.73 to 9.0 eV, for polarization along directions a, b, and c of the orthorhombic unit cell. A Kramers–Kronig consistent parameterized model was utilized to identify critical point structures and their association with band-to-band transitions, and the results from density functional theory (DFT) calculations for the electronic band structure of NdGaO<sub>3</sub> are compared. A Cauchy parameter analysis for the three refractive indices is performed in the below bandgap spectral range. Dielectric functions along lattice directions a, b, and c and their respective bandgap energy values are very similar. Below the bandgap energy, the refractive index differences for directions a and b are very small (0.34% on average) while index differences with direction c (approximately 1.25%) lead to effective positive uniaxial optical properties (n <sub>c</sub> &gt; n <sub>a</sub> ≈ n <sub>b</sub>) toward the phonon modes spectral range. Our ellipsometry analysis determines the lowest band-to-band transitions of NdGaO3 to occur at E <sub>a</sub> = 6.46 (6) eV, E <sub>b</sub> = 6.29 (5) eV, and E <sub>c</sub> = 6.77 (7) eV, i.e., E <sub>c</sub> &gt; E <sub>a</sub> &gt; E <sub>b</sub>, while our DFT calculations predict the first transition to be lowest along the a axis. We discuss our findings in light of previous reports and present all parameters of our theoretical and experimental analyses.</p>}},
  author       = {{Traouli, Yousra and Kilic, Ufuk and Korlacki, Rafał and Hilfiker, Matthew and Mock, Alyssa and Schubert, Eva and Schubert, Mathias}},
  issn         = {{0021-8979}},
  language     = {{eng}},
  number       = {{13}},
  publisher    = {{American Institute of Physics (AIP)}},
  series       = {{Journal of Applied Physics}},
  title        = {{Electronic band structure, band-to-band transitions, and anisotropic dielectric functions of orthorhombic NdGaO<sub>3</sub>}},
  url          = {{http://dx.doi.org/10.1063/5.0320451}},
  doi          = {{10.1063/5.0320451}},
  volume       = {{139}},
  year         = {{2026}},
}