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Anisotropic dielect...
Anisotropic dielectric function, direction dependent bandgap energy, band order, and indirect to direct gap crossover in α-(AlxGa1−x)2O3 (0≤?≤10≤x≤1)
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- Hilfiker, Matthew (author)
- Univ Nebraska Lincoln, NE 68588 USA
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- Kilic, Ufuk (author)
- Univ Nebraska Lincoln, NE 68588 USA
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- Stokey, Megan (author)
- Univ Nebraska Lincoln, NE 68588 USA
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- Jinno, Riena (author)
- Cornell Univ, NY 14853 USA; Kyoto Univ, Japan
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- Cho, Yongjin (author)
- Cornell Univ, NY 14853 USA
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- Xing, Huili Grace (author)
- Cornell Univ, NY 14853 USA; Cornell Univ, NY 14853 USA
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- Jena, Debdeep (author)
- Cornell Univ, NY 14853 USA; Cornell Univ, NY 14853 USA
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- Korlacki, Rafal (author)
- Univ Nebraska Lincoln, NE 68588 USA
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- Schubert, Mathias (author)
- Linköpings universitet,Halvledarmaterial,Tekniska fakulteten,Univ Nebraska Lincoln, NE 68588 USA,Centre for III-nitride technology (C3NiT)
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(creator_code:org_t)
- AIP Publishing, 2022
- 2022
- English.
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:5
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- Mueller matrix spectroscopic ellipsometry is applied to determine anisotropic optical properties for a set of single-crystal rhombohedral structure alpha-(AlxGa1-x)(2)O-3 thin films (0 <= x <= 1). Samples are grown by plasma-assisted molecular beam epitaxy on m-plane sapphire. A critical-point model is used to render a spectroscopic model dielectric function tensor and to determine direct electronic band-to-band transition parameters, including the direction dependent two lowest-photon energy band-to-band transitions associated with the anisotropic bandgap. We obtain the composition dependence of the direction dependent two lowest band-to-band transitions with separate bandgap bowing parameters associated with the perpendicular (b(Eg,⊥) = 1.31 eV) and parallel (b(Eg,||) = 1.61 eV) electric field polarization to the lattice c direction. Our density functional theory calculations indicate a transition from indirect to direct characteristics between alpha-Ga2O3 and alpha-Al2O3, respectively, and we identify a switch in band order where the lowest band-to-band transition occurs with polarization perpendicular to c in alpha-Ga2O3 whereas for alpha-Al2O3 the lowest transition occurs with polarization parallel to c. We estimate that the change in band order occurs at approximately 40% Al content. Additionally, the characteristic of the lowest energy critical point transition for polarization parallel to c changes from M-1 type in alpha-Ga2O3 to M-0 type van Hove singularity in alpha-Al2O3.
Subject headings
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Publication and Content Type
- ref (subject category)
- art (subject category)
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