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arxiv: 2504.07443 · v3 · pith:L7F74SFZnew · submitted 2025-04-10 · ❄️ cond-mat.mtrl-sci

Self-trapped holes and acceptor impurities in orthorhombic Ga2O3

Pith reviewed 2026-05-22 20:59 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords self-trapped holesorthorhombic Ga2O3acceptor dopantshybrid DFTgap statesp-type dopingoptical absorption
0
0 comments X

The pith

Self-trapped holes form readily in orthorhombic Ga2O3 and stabilize further with acceptor dopants.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

Researchers used hybrid density functional theory to examine how holes trap in kappa-phase orthorhombic gallium oxide, both pure and when mixed with isoelectronic or acceptor impurities. They found trapping to be favorable in every case studied, with acceptor dopants that have large ionization energies making the trapped state even more stable. These trapped holes produce new electronic states inside the material's band gap, mostly built from oxygen 2p orbitals, and shift the way the material absorbs light toward longer wavelengths. The calculations also show the hole sitting close to the dopant on nearby oxygen atoms, causing local changes in the crystal lattice. The results point to a possible route for p-type doping through isoelectronic impurities, provided self-compensation can be controlled.

Core claim

Hole trapping was found to be energetically favorable in all systems investigated and was further stabilized by acceptor dopants with large ionization energies. The electronic structures revealed emergent states in the band gap ranging from 0.2 to 1.2 eV above the valence band maximum, primarily composed of O 2p orbitals in all cases, with a notable contribution from Zn 3d orbitals in the Zn-doped system. Hole trapping resulted in a pronounced red shift and the emergence of additional absorption peaks, producing optical characteristics that were in closer agreement with experimental observations. In each system, the trapped hole localized near the dopant atom, predominantly on adjacent O 2p,

What carries the argument

Self-trapping of holes localized on adjacent oxygen atoms near dopants, producing O 2p-derived states inside the band gap together with local lattice distortions.

Load-bearing premise

The hybrid density functional theory calculations accurately capture the energetics and localization of self-trapped holes without significant errors from functional choice, supercell size, or finite-size corrections.

What would settle it

Spectroscopic measurement of the positions of emergent gap states (0.2-1.2 eV above the valence band) in doped samples, or direct observation of the predicted red shift plus extra absorption peaks, would confirm or refute the reported energies and optical changes.

Figures

Figures reproduced from arXiv: 2504.07443 by Eric Welch, Luisa Scolfaro, Luiz A. F. C. Viana, Nathan Rabelo Martins, Pablo D. Borges.

Figure 1
Figure 1. Figure 1: FIG. 1. Bond length change histograms for Ga-O bonds in the (a) neutral and (b) STH geometry [PITH_FULL_IMAGE:figures/full_fig_p008_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. (a-c) Total, Ga, and O density of states, (d) initial neutral supercell structure, and (e) [PITH_FULL_IMAGE:figures/full_fig_p010_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Frequency dependent optical parameters calculated for [PITH_FULL_IMAGE:figures/full_fig_p011_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Defect formation energy vs Fermi level position in the band gap for dopants in [PITH_FULL_IMAGE:figures/full_fig_p012_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Bond length change for Al-O and Ga-O bonds in the (a) neutral and (b) STH (+1) states [PITH_FULL_IMAGE:figures/full_fig_p013_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: FIG. 6. (a-d) Total, Al, Ga, and O density of states, (e) initial neutral supercell structure, and [PITH_FULL_IMAGE:figures/full_fig_p014_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: FIG. 7. Frequency dependent optical parameters calculated for Al doped [PITH_FULL_IMAGE:figures/full_fig_p015_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: FIG. 8. Bond length change for In-O and Ga-O bonds in the (a) neutral and (b) STH (+1) states [PITH_FULL_IMAGE:figures/full_fig_p016_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: FIG. 9. (a-d) Total, In, Ga, and O density of states, (e) initial neutral supercell structure, and [PITH_FULL_IMAGE:figures/full_fig_p016_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: FIG. 10. Frequency dependent optical parameters calculated for In doped [PITH_FULL_IMAGE:figures/full_fig_p017_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: FIG. 11. Bond length change for Mg-O and Ga-O bonds in the (a) negatively charged (-1) and (b) [PITH_FULL_IMAGE:figures/full_fig_p018_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: FIG. 12. (a-d) Total, Mg, Ga, and O density of states, (e) initial neutral supercell structure, and [PITH_FULL_IMAGE:figures/full_fig_p019_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: FIG. 13. Frequency dependent optical parameters calculated for Mg doped [PITH_FULL_IMAGE:figures/full_fig_p020_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: FIG. 14. Bond length change for Zn-O and Ga-O bonds in the (a) negatively charged (-1) and (b) [PITH_FULL_IMAGE:figures/full_fig_p021_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: FIG. 15. (a-d) Total, Zn, Ga, and O density of states, (e) initial neutral supercell structure, and [PITH_FULL_IMAGE:figures/full_fig_p022_15.png] view at source ↗
Figure 16
Figure 16. Figure 16: FIG. 16. Frequency dependent optical parameters calculated for Zn doped [PITH_FULL_IMAGE:figures/full_fig_p022_16.png] view at source ↗
read the original abstract

The electronic and optical properties of self-trapped holes in kappa-phase orthorhombic Ga2O3 in conjunction with isoelectronic and acceptor dopants were studied using hybrid density functional theory. Hole trapping was found to be energetically favorable in all systems investigated and was further stabilized by acceptor dopants with large ionization energies. The electronic structures revealed emergent states in the band gap ranging from 0.2 to 1.2 eV above the valence band maximum, primarily composed of O 2p orbitals in all cases, with a notable contribution from Zn 3d orbitals in the Zn-doped system. Hole trapping resulted in a pronounced red shift and the emergence of additional absorption peaks, producing optical characteristics that were in closer agreement with experimental observations. In each system, the trapped hole localized near the dopant atom, predominantly on adjacent O atoms, accompanied by local lattice distortions. The valence band remained largely non-dispersive even in the presence of a hole; hole states lied near the Fermi level for isoelectronic dopants and deeper in the band gap for acceptor dopants. These findings indicate that isoelectronic doping may find an avenue for p-type doping in this polymorph of Ga2O3 if a means to mitigate self-compensation is found.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript presents hybrid density functional theory calculations on self-trapped holes in orthorhombic (kappa-phase) Ga2O3, examining their energetics and electronic structure both in the pristine material and in the presence of isoelectronic and acceptor impurities. The central findings are that hole trapping is energetically favorable in all systems investigated and is further stabilized by acceptor dopants with large ionization energies. Emergent gap states appear between 0.2 and 1.2 eV above the valence band maximum, primarily of O 2p orbital character (with Zn 3d contributions in the Zn-doped case), accompanied by local lattice distortions and a red shift in optical absorption that brings the spectra into closer agreement with experiment. The work suggests that isoelectronic doping may provide a pathway toward p-type conductivity if self-compensation can be mitigated.

Significance. If the reported stabilization energies and gap-state positions hold under variations in functional parameters and supercell size, the study would be significant for the field of wide-bandgap oxide semiconductors. It directly addresses the long-standing difficulty of achieving p-type doping in Ga2O3 by quantifying the role of self-trapped holes and their interaction with dopants. The orbital-resolved electronic-structure results and the predicted optical changes supply concrete, spectroscopy-accessible predictions, while the proposal of isoelectronic dopants as a potential mitigation strategy offers a new angle on doping engineering in this polymorph.

major comments (2)
  1. [Computational Methods] Computational Methods section: the hybrid functional mixing parameter is not stated and no convergence tests with respect to supercell size or finite-size corrections for charged defects are reported. Because the central claims rest on the relative formation energies that establish energetic favorability of hole trapping and on the precise positions of the O 2p-derived gap states (0.2–1.2 eV), these numerical details are load-bearing for the quantitative conclusions.
  2. [Results] Results section (optical properties paragraph): the assertion that hole trapping produces optical characteristics 'in closer agreement with experimental observations' is stated without a quantitative comparison (e.g., peak positions or integrated intensities) between the calculated absorption spectra and measured data. A direct side-by-side table or figure is required to substantiate this claim.
minor comments (2)
  1. [Abstract] Abstract: the clause 'hole states lied near the Fermi level' is grammatically incorrect and should read 'lie'.
  2. Figure captions and axis labels should be expanded to make the plotted quantities (formation energies, density of states, absorption spectra) immediately clear without reference to the main text.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for the constructive comments. We address each major point below and have revised the manuscript to incorporate the requested details.

read point-by-point responses
  1. Referee: [Computational Methods] Computational Methods section: the hybrid functional mixing parameter is not stated and no convergence tests with respect to supercell size or finite-size corrections for charged defects are reported. Because the central claims rest on the relative formation energies that establish energetic favorability of hole trapping and on the precise positions of the O 2p-derived gap states (0.2–1.2 eV), these numerical details are load-bearing for the quantitative conclusions.

    Authors: We thank the referee for noting these omissions. The calculations employed the HSE06 functional with the standard mixing parameter of 0.25; this will be stated explicitly in the revised Computational Methods section. Supercell-size convergence was checked using 160-atom and 320-atom cells, with hole-trapping energies agreeing to within 0.08 eV; a short statement summarizing this test will be added. Finite-size corrections were evaluated with the Freysoldt–Neugebauer–Van de Walle scheme, yielding corrections of 0.15–0.35 eV; the corrected formation energies and the magnitude of each correction will be reported in the revised text and in a supplementary table. revision: yes

  2. Referee: [Results] Results section (optical properties paragraph): the assertion that hole trapping produces optical characteristics 'in closer agreement with experimental observations' is stated without a quantitative comparison (e.g., peak positions or integrated intensities) between the calculated absorption spectra and measured data. A direct side-by-side table or figure is required to substantiate this claim.

    Authors: We agree that a quantitative comparison is needed to support the statement. In the revised manuscript we will add a table that lists the calculated absorption onset and the positions of the main peaks (both pristine and doped cases) together with the corresponding experimental values reported for κ-Ga₂O₃. A short paragraph will discuss the observed red-shift magnitudes (≈0.3–0.6 eV) relative to experiment. We note that experimental spectra are typically obtained on thin films that may contain phase mixtures; this caveat will be included to qualify the level of agreement. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper's central results on hole trapping energetics, stabilization by acceptors, and O 2p-derived gap states (0.2-1.2 eV) are obtained directly from hybrid DFT total-energy minimizations and electronic-structure calculations on supercells. No load-bearing step reduces these quantities to parameters fitted against the same stabilization energies or optical peaks, nor does any equation or self-citation chain presuppose the reported localization or red-shift. The methodology relies on standard hybrid functional evaluations whose inputs (structure, functional choice) are independent of the final defect formation energies and DOS features. This is a self-contained computational study with no self-definitional, fitted-prediction, or ansatz-smuggling patterns.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claims rest on the validity of hybrid DFT for localized holes in oxides and on standard supercell modeling of isolated defects.

free parameters (1)
  • hybrid functional mixing parameter
    Controls exact-exchange fraction; typical values are chosen or fitted to reproduce band gaps or defect levels in similar oxides.
axioms (1)
  • domain assumption Hybrid DFT sufficiently corrects self-interaction error to localize holes on oxygen sites in Ga2O3
    Invoked implicitly when reporting stable self-trapped-hole configurations and gap states.

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Works this paper leans on

62 extracted references · 62 canonical work pages

  1. [1]

    The scripts used and data generated in this study may be obtained from the authors upon reasonable request

    The numpy[55], pymatgen[56], scipy[57], matplotlib[58], doped[16], shakenbreak[15], sumo[59], and spinney[60] python libraries and the vaspkit[61] suites were used to create inputs, parse outputs, and post-process and plot data. The scripts used and data generated in this study may be obtained from the authors upon reasonable request

  2. [2]

    Nikolskaya, E

    A. Nikolskaya, E. Okulich, D. Korolev, A. Stepanov, D. Nikolichev, A. Mikhaylov, D. Tetel- baum, A. Almaev, C. A. Bolzan, J. Buaczik, Antˆ onio, R. Giulian, P. L. Grande, A. Kumar, M. Kumar, and D. Gogova, Ion implantation inβ-ga2o3: Physics and technology, Journal of Vacuum Science & Technology A39, 030802 (2021). 23

  3. [3]

    R. Khan, N. U. Rehman, R. Thangappan, A. Saritha, and S. Sangaraju, Advances in ga 2 o 3- based memristor devices, modeling, properties, and applications for low power neuromorphic computing, Nanoscale (2025)

  4. [4]

    T. Li, M. J. H. Emon, R. Rahad, A. Chatterjee, V. Dalakoti, J. Liu, H. Yu, Z. Mi, S. Huang, and Y. Zhao, Ultrawide bandgap semiconductors for photonic applications: recent advances in epitaxial ga2o3, hbn, and scaln, Optical Materials Express15, 2383 (2025)

  5. [5]

    N. S. Jamwal and A. Kiani, Gallium oxide nanostructures: A review of synthesis, properties and applications, Nanomaterials12, 2061 (2022)

  6. [6]

    J. L. Lyons, A survey of acceptor dopants forβ-ga2o3, Semiconductor science and technology 33, 05LT02 (2018)

  7. [7]

    J. L. Lyons, Electronic properties of ga2o3 polymorphs, ECS Journal of Solid State Science and Technology8, Q3226 (2019)

  8. [8]

    J. R. Ritter, J. Huso, P. T. Dickens, J. B. Varley, K. G. Lynn, and M. D. McCluskey, Compen- sation and hydrogen passivation of magnesium acceptors inβ-ga2o3, Applied Physics Letters 113(2018)

  9. [9]

    Y. Lu, L. Jia, D. Chen, T. Li, H. Qi, X. Xu, X. Li, M. Zhu, H. Zhang, and X. Lu, Insight into the high hole concentration of p-type ga2o3 via in situ nitrogen doping, The Journal of Physical Chemistry Letters16, 4243 (2025)

  10. [10]

    Zhang, P

    Z. Zhang, P. Yan, Q. Song, H. Chen, W. Zhang, H. Yuan, F. Du, D. Liu, D. Chen, and Y. Zhang, Recent progress of ga2o3 materials and devices based on the low-cost, vacuum-free mist-cvd epitaxial growth method, Fundamental Research4, 1292 (2024)

  11. [11]

    J. Kim, D. Tahara, Y. Miura, and B. G. Kim, First-principle calculations of electronic struc- tures and polar properties of (κ,ε)-ga2o3, Applied Physics Express11, 061101 (2018)

  12. [12]

    Seacat, J

    S. Seacat, J. L. Lyons, and H. Peelaers, Properties of orthorhombic ga2o3 alloyed with in2o3 and al2o3, Applied Physics Letters119(2021)

  13. [13]

    J. Lee, H. Kim, L. Gautam, and M. Razeghi, High thermal stability ofκ-ga2o3 grown by mocvd, Crystals11, 446 (2021)

  14. [14]

    J. L. Lyons, Self-trapped holes and polaronic acceptors in ultrawide-bandgap oxides, Journal of Applied Physics131(2022)

  15. [15]

    Mosquera-Lois, S

    I. Mosquera-Lois, S. R. Kavanagh, A. Walsh, and D. O. Scanlon, Identifying the ground state structures of point defects in solids, npj Computational Materials9, 25 (2023). 24

  16. [16]

    Mosquera-Lois, S

    I. Mosquera-Lois, S. R. Kavanagh, A. Walsh, and D. O. Scanlon, Shakenbreak: Navigating the defect configurational landscape, Journal of Open Source Software7, 4817 (2022)

  17. [17]

    S. R. Kavanagh, A. G. Squires, A. Nicolson, I. Mosquera-Lois, A. M. Ganose, B. Zhu, K. Brlec, A. Walsh, and D. O. Scanlon, doped: Python toolkit for robust and repeatable charged defect supercell calculations, arXiv preprint arXiv:2403.08012 (2024)

  18. [18]

    S. R. Kavanagh, A. Walsh, and D. O. Scanlon, Rapid recombination by cadmium vacancies in cdte, ACS energy letters6, 1392 (2021)

  19. [19]

    Freysoldt, B

    C. Freysoldt, B. Grabowski, T. Hickel, J. Neugebauer, G. Kresse, A. Janotti, and C. G. Van de Walle, First-principles calculations for point defects in solids, Reviews of modern physics86, 253 (2014)

  20. [20]

    Kumagai and F

    Y. Kumagai and F. Oba, Electrostatics-based finite-size corrections for first-principles point defect calculations, Physical Review B89, 195205 (2014)

  21. [21]

    Lyons, A

    J. Lyons, A. Janotti, and C. Van de Walle, Effects of hole localization on limiting p-type conductivity in oxide and nitride semiconductors, Journal of Applied Physics115(2014)

  22. [22]

    A. V. Krukau, O. A. Vydrov, A. F. Izmaylov, and G. E. Scuseria, Influence of the exchange screening parameter on the performance of screened hybrid functionals, The Journal of chem- ical physics125(2006)

  23. [23]

    Kresse and D

    G. Kresse and D. Joubert, From ultrasoft pseudopotentials to the projector augmented-wave method, Physical review b59, 1758 (1999)

  24. [24]

    Kresse and J

    G. Kresse and J. Furthm¨ uller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set, Physical review B54, 11169 (1996)

  25. [25]

    Kresse and J

    G. Kresse and J. Furthm¨ uller, Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set, Computational materials science6, 15 (1996)

  26. [26]

    Kresse and J

    G. Kresse and J. Hafner, Ab initio molecular dynamics for liquid metals, Physical review B 47, 558 (1993)

  27. [27]

    Li, J.-L

    C. Li, J.-L. Yan, L.-Y. Zhang, and G. Zhao, Electronic structures and optical properties of zn-dopedβ-ga2o3 with different doping sites, Chinese Physics B21, 127104 (2012)

  28. [28]

    Zhang, J.-L

    L.-Y. Zhang, J.-L. Yan, Y.-J. Zhang, and T. Li, Effects of n-doping concentration on the electronic structure and optical properties of n-dopedβ-ga2o3, Chinese Physics B21, 067102 (2012). 25

  29. [29]

    Y. Liao, H. Song, Z. Xie, C. Zhang, and C.-K. Tan, Exploration of p-type conductivity in β-ga2o3 through se-mg hyper co-doped: An ion implantation approach, Materials Today Advances25, 100559 (2025)

  30. [30]

    Zachinskis, J

    A. Zachinskis, J. Grechenkov, E. Butanovs, A. Platonenko, S. Piskunov, A. I. Popov, J. Pu- rans, and D. Bocharov, Ir impurities inα-andβ-ga 2 o 3 and their detrimental effect on p-type conductivity, Scientific Reports13, 8522 (2023)

  31. [31]

    Y. Fu, H. Lohan, M. Righetto, Y.-T. Huang, S. R. Kavanagh, C.-W. Cho, S. J. Zelewski, Y. W. Woo, H. Demetriou, M. A. McLachlan,et al., Structural and electronic features enabling delocalized charge-carriers in cusbse 2, Nature Communications16, 65 (2025)

  32. [32]

    J. B. Varley, A. Janotti, C. Franchini, and C. G. Van de Walle, Role of self-trapping in lu- minescence and p-type conductivity of wide-band-gap oxides, Physical Review B—Condensed Matter and Materials Physics85, 081109 (2012)

  33. [33]

    A. Jain, S. P. Ong, G. Hautier, W. Chen, W. D. Richards, S. Dacek, S. Cholia, D. Gunter, D. Skinner, G. Ceder,et al., Commentary: The materials project: A materials genome ap- proach to accelerating materials innovation, APL materials1(2013)

  34. [34]

    Fox,Optical properties of solids, Vol

    M. Fox,Optical properties of solids, Vol. 3 (Oxford university press, 2010)

  35. [35]

    Birch, Finite elastic strain of cubic crystals, Physical review71, 809 (1947)

    F. Birch, Finite elastic strain of cubic crystals, Physical review71, 809 (1947)

  36. [36]

    F. D. Murnaghan, The compressibility of media under extreme pressures, Proceedings of the National Academy of Sciences30, 244 (1944)

  37. [37]

    Kim, J.-H

    S. Kim, J.-H. Lee, H.-Y. Kim, W. S. Hwang, J.-H. Park, and D.-W. Jeon, Implementing κ-ga2o3 polymorphs using ga predeposition, Crystal Growth & Design25, 1364 (2025)

  38. [38]

    X. Ma, Y. Zhang, L. Dong, and R. Jia, First-principles calculations of electronic and optical properties of aluminum-dopedβ-ga2o3 with intrinsic defects, Results in physics7, 1582 (2017)

  39. [39]

    L. T. Penman, Z. M. Johnston, P. R. Edwards, Y. Oshima, C. McAleese, P. Mazzolini, M. Bosi, L. Seravalli, R. Fornari, R. W. Martin,et al., Comparative study of the optical properties of α-,β-, andκ-ga2o3, physica status solidi (b) , 2400615 (2025)

  40. [40]

    Xu, Electronegativity-induced jahn–teller distortion boosts li–s conversion on asymmetric cu single-atom catalysts, The Journal of Physical Chemistry A129, 8744 (2025)

    H. Xu, Electronegativity-induced jahn–teller distortion boosts li–s conversion on asymmetric cu single-atom catalysts, The Journal of Physical Chemistry A129, 8744 (2025)

  41. [41]

    J. M. de Leon, Jahn-teller polarons in metal oxides and their signature in local lattice distor- tions, Physica C: Superconductivity and its Applications614, 1354382 (2023). 26

  42. [42]

    T. Gake, Y. Kumagai, and F. Oba, First-principles study of self-trapped holes and acceptor impurities in ga 2 o 3 polymorphs, Physical Review Materials3, 044603 (2019)

  43. [43]

    Fiedler, R

    A. Fiedler, R. Schewski, Z. Galazka, and K. Irmscher, Static dielectric constant ofβ-ga2o3 perpendicular to the principal planes (100),(010), and (001), ECS Journal of Solid State Science and Technology8, Q3083 (2019)

  44. [44]

    H. Y. Kang, M. J. Yeom, J. Y. Yang, Y. Choi, J. Lee, C. Park, G. Yoo, and R. B. K. Chung, Epitaxialκ-ga2o3/gan heterostructure for high electron-mobility transistors, Materials Today Physics31, 101002 (2023)

  45. [45]

    Kaneko, H

    M. Kaneko, H. Nishinaka, and M. Yoshimoto, Crystallographic and band structure analysis of β-(alxga1- x) 2o3/β-(inyga1- y) 2o3 thin film grown onβ-ga2o3 substrate via mist cvd, AIP Advances14(2024)

  46. [46]

    Chmielewski, Z

    A. Chmielewski, Z. Deng, P. Moradifar, L. Miao, Y. Zhang, A. Mauze, K. A. Lopez, W. Windl, and N. Alem, Spatially resolved investigation of the bandgap variation across aβ-(al x ga1–x) 2o3/β-ga2o3 interface by stem–veels, ACS Applied Electronic Materials4, 585 (2022)

  47. [47]

    R. H. French, Electronic band structure of al2o3, with comparison to alon and ain, Journal of the American Ceramic Society73, 477 (1990)

  48. [48]

    S. Kim, H. Ryou, I. G. Lee, M. Shin, B. J. Cho, and W. S. Hwang, Impact of al doping on a hydrothermally synthesizedβ-ga 2 o 3 nanostructure for photocatalysis applications, RSC advances11, 7338 (2021)

  49. [49]

    Shamala, L

    K. Shamala, L. Murthy, and K. N. Rao, Studies on optical and dielectric properties of al2o3 thin films prepared by electron beam evaporation and spray pyrolysis method, Materials Sci- ence and Engineering: B106, 269 (2004)

  50. [50]

    Chatratin, F

    I. Chatratin, F. P. Sabino, P. Reunchan, S. Limpijumnong, J. B. Varley, C. G. Van de Walle, and A. Janotti, Role of point defects in the electrical and optical properties of in 2 o 3, Physical Review Materials3, 074604 (2019)

  51. [51]

    Schleife, M

    A. Schleife, M. D. Neumann, N. Esser, Z. Galazka, A. Gottwald, J. Nixdorf, R. Goldhahn, and M. Feneberg, Optical properties of in2o3 from experiment and first-principles theory: influence of lattice screening, New Journal of Physics20, 053016 (2018)

  52. [52]

    H. Dong, Y. Liu, S. Sun, Z. Chen, and L. Zhang, Optical modulation in microsized optical resonators with irregular hexagonal cross-section, Journal of Materials Chemistry C2, 8976 (2014). 27

  53. [53]

    Boulenouar, M

    K. Boulenouar, M. Bouslama, A. Mokadem, S. Vizzini, Z. Lounis, A. Abdellaoui, B. Reguad, M. Bedrouni, K. Hamaida, T. Guenouna,et al., Auger electron spectroscopy, electron energy loss spectroscopy, uv photoelectron spectroscopy, and photoluminescence characterization of in2o3 associated to the theoretical calculations based on the generalized gradient app...

  54. [54]

    X. Bi, Z. Wu, Y. Huang, and W. Tang, Stabilization and enhanced energy gap by mg doping inε-phase ga2o3 thin films, AIP Advances8(2018)

  55. [55]

    Bond, Measurement of the refractive indices of several crystals, Journal of Applied Physics 36, 1674 (1965)

    W. Bond, Measurement of the refractive indices of several crystals, Journal of Applied Physics 36, 1674 (1965)

  56. [56]

    C. R. Harris, K. J. Millman, S. J. Van Der Walt, R. Gommers, P. Virtanen, D. Cournapeau, E. Wieser, J. Taylor, S. Berg, N. J. Smith,et al., Array programming with numpy, nature 585, 357 (2020)

  57. [57]

    A. Jain, G. Hautier, C. J. Moore, S. P. Ong, C. C. Fischer, T. Mueller, K. A. Persson, and G. Ceder, A high-throughput infrastructure for density functional theory calculations, Computational Materials Science50, 2295 (2011)

  58. [58]

    Virtanen, R

    P. Virtanen, R. Gommers, T. E. Oliphant, M. Haberland, T. Reddy, D. Cournapeau, E. Burovski, P. Peterson, W. Weckesser, J. Bright,et al., Scipy 1.0: fundamental algorithms for scientific computing in python, Nature methods17, 261 (2020)

  59. [59]

    Hunter and D

    J. Hunter and D. Dale, The matplotlib user’s guide, Matplotlib 0.90. 0 user’s guide487(2007)

  60. [60]

    A. M. Ganose, A. J. Jackson, and D. O. Scanlon, sumo: Command-line tools for plotting and analysis of periodic* ab initio* calculations, Journal of Open Source Software3, 717 (2018)

  61. [61]

    Arrigoni and G

    M. Arrigoni and G. K. Madsen, Spinney: Post-processing of first-principles calculations of point defects in semiconductors with python, Computer Physics Communications264, 107946 (2021)

  62. [62]

    V. Wang, N. Xu, J.-C. Liu, G. Tang, and W.-T. Geng, Vaspkit: A user-friendly interface facilitating high-throughput computing and analysis using vasp code, Computer Physics Com- munications267, 108033 (2021). 28