Amanda Langørgen

• Langørgen, Amanda; Frodason, Ymir Kalmann; Karsthof, Robert Michael; Von Wenckstern, Holger; Jensen, Ingvild Julie Thue & Vines, Lasse [Show all 7 contributors for this article] (2023). Defect level in κ-Ga2O3 revealed by thermal admittance spectroscopy. Journal of Applied Physics. ISSN 0021-8979. 134(1), p. 015701-1–015701-6. doi: 10.1063/5.0150994. Full text in Research Archive Show summary

  Defects in pulsed-laser deposition grown have been investigated using thermal admittance spectroscopy and secondary ion mass spectrometry (SIMS). A film was grown on either a tin-doped indium oxide or an aluminum-doped zinc oxide buffer layer on a sapphire substrate functioning as back contact layer in vertical diode structures. In both sample types, a distinct signature in the capacitance signal was observed in the temperature range of 150–260 K. The corresponding defect charge-state transition level, labeled ⁠, was found to exhibit an activation energy of 0.21 eV. Potential candidates for the level were investigated using a combination of SIMS and hybrid-functional calculations. SIMS revealed the main impurities in the sample to be tin, silicon, and iron. The hybrid-functional calculations predict the acceptor levels of substitutional iron to lie 0.7–1.2 eV below the conduction band minimum depending on Ga-site, making an unlikely candidate for the level. Furthermore, Si as well as Sn substituting on the sixfold coordinated Ga2 site and the fivefold coordinated Ga3 and Ga4 sites are all shallow donors in -⁠, similar to that of -⁠. Sn substituting on the fourfold Ga1 site is, however, predicted to have levels in the bandgap at 0.15 and 0.24 eV below the conduction band minimum, in accordance with the extracted activation energy for ⁠. Thus, we tentatively assign as the origin of the level.

• Polyakov, A.Y.; Kochkova, A.I.; Langørgen, Amanda; Vines, Lasse; Vasilev, A. & Shchemerov, I.V. [Show all 8 contributors for this article] (2023). On the possible nature of deep centers in Ga2O3. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. ISSN 0734-2101. 41(2), p. 023401-1–023401-6. doi: 10.1116/6.0002307. Full text in Research Archive Show summary

  The electric field dependence of emission rate of the deep traps with level near Ec−0.6 eV, so-called E1 traps, was studied by means of deep level transient spectroscopy measurements over a wide range of applied voltages. The traps were initially introduced by 900 °C ampoule annealing in molecular hydrogen. The results indicate the activation energy of the centers and the ratio of high-field to low-field electron emission rates at a fixed temperature scale as the square root of electric field, suggesting that the centers behave as deep donors. The possible microscopic nature of the centers in view of recent theoretical calculations is discussed. The most likely candidates for the E1 centers are SiGa1–H or SnGa2–H complexes.

• Langørgen, Amanda; Zimmermann, Christian; Frodason, Ymir Kalmann; Verhoeven, Espen Førdestrøm; Weiser, Philip Michael & Karsthof, Robert Michael [Show all 8 contributors for this article] (2022). Influence of heat treatments in H2 and Ar on the E1 center in β-Ga2O3. Journal of Applied Physics. ISSN 0021-8979. 131(115702). doi: 10.1063/5.0083861. Full text in Research Archive

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• Langørgen, Amanda; Frodason, Ymir Kalmann; Julie Thue Jensen, Ingvild & Vines, Lasse (2023). A metastable deep defect in beta-Ga2O3.
• Langørgen, Amanda; Frodason, Ymir Kalmann; Karsthof, Robert Michael; Wenckstern, Holger von; Thue Jensen, Ingvild & Vines, Lasse (2022). An electron trap in κ-Ga2O3 and the quest for its microscopic origin.
• Zimmermann, Christian; Frodason, Ymir Kalmann; Varley, Joel Basile; Verhoeven, Espen Førdestrøm; Rønning, Vegard & Weiser, Philip Michael [Show all 15 contributors for this article] (2021). Identification of Fe-, Ti- and H-related Charge-state Transition Levels in β-Ga2O3.
• Langørgen, Amanda; Karsthof, Robert Michael; Weiser, Philip Michael; Cavani, Olivier; Grasset, Romain & Frodason, Ymir Kalmann [Show all 8 contributors for this article] (2021). Steady-state Photocapacitance Spectroscopy of Intrinsic Defects in Electron-Irradiated β-Ga₂O₃.
• Olsen, Vegard Skiftestad; Karlsen, Kjetil; Langørgen, Amanda; Andreassen, Magnus & Knausgård Hommedal, Ylva (2021). Omvisning UiO MiNaLab for FA bachelorstudenter.

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