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Long-Wavelength Spectroscopy of Phonon Properties in Wide Bandgap Semiconducting Oxides
Generalized spectroscopic ellipsometry provides a means to capture the full description of the light-matter interaction via the Mueller matrix. By modeling this matrix, the full dielectric tensor function is obtained. In long-wavelength ellipsometry, the infrared-active phonon modes are the primary features seen in the dielectric function and as such, can be identified and described in full. This technique proves particularly powerful when analyzing highly anisotropic optical behavior in low-symmetry materials. One such material class gaining relevance is wide bandgap semiconducting oxides. These semiconducting crystals have tremendous potential for applications in power electronics and beyond as they have improved breakdown fields over industry standard silicon technologies. In this work, long-wavelength generalized spectroscopic ellipsometry is utilized in combination with density functional theory calculations to extract the dielectric function tensors of several wide bandgap semiconductors including zinc gallate, indium oxide, lutetium oxyorthosilicate, and alloyed gallium oxides. From these dielectric function tensors, relevant electronic material properties are extracted such as infrared-active phonon modes, dielectric constants, and free-charge carrier properties. Furthermore, the alloying-induced and strain-induced changes to these properties (where present) are also deduced independently by using a combined density functional theory calculation and experimental approach.
Electrical engineering|Physics|Physical chemistry
Stokey, Megan, "Long-Wavelength Spectroscopy of Phonon Properties in Wide Bandgap Semiconducting Oxides" (2023). ETD collection for University of Nebraska - Lincoln. AAI30486439.