Anisotropic dielectric functions, band-to-band transitions, and critical points in <b><i>α</i></b>-Ga<sub>2</sub>O<sub>3</sub>
نویسندگان
چکیده
We use a combined generalized spectroscopic ellipsometry and density functional theory approach to determine analyze the anisotropic dielectric functions of an α-Ga2O3 thin film. The sample is grown epitaxially by plasma-assisted molecular beam epitaxy on m-plane sapphire. Generalized data from multiple azimuths in spectral range 0.73 eV 8.75 are simultaneously analyzed. Density used calculate valence conduction band structure. identify, for indirect-bandgap material, two direct band-to-band transitions with M0-type van Hove singularities polarization perpendicular c axis, E 0 , ⊥ = 5.46 ( 6 ) 6.04 1 eV, one transition M1-type singularity parallel | 5.44 2 eV. further identify excitonic contributions small binding energy 7 meV associated lowest ordinary hyperbolic exciton at critical point large 178 meV.
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ژورنال
عنوان ژورنال: Applied Physics Letters
سال: 2021
ISSN: ['1520-8842', '0003-6951', '1077-3118']
DOI: https://doi.org/10.1063/5.0031424