Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Oxide Semiconductors I
HL 25.3: Vortrag
Mittwoch, 20. März 2024, 10:00–10:15, ER 325
Comparative study of temperature-dependent bandgap transitions in Ga2O3 polymorphs — •Benjamin M. Janzen1, Nima Hajizadeh1, Moritz Meißner1, Marcella N. Marggraf1, Conrad V. Hartung1, Alwin Wüthrich1, Nils Bernhardt1, Felix Nippert1, and Markus R. Wagner2 — 1Technische Universität Berlin — 2Paul-Drude-Institut für Festkörperelektronik
The temperature dependence of the optical bandgap has rarely been investigated experimentally for the different polymorphs of Ga2O3. A direct comparison of the temperature dependence as well as the electron-phonon coupling strengths is made considerably more difficult by the different experimental methods (e.g., reflection spectroscopy, absorption spectroscopy or ellipsometry) used to study the various polymorphs. In particular, there is no study in the literature that provides a self-consistent comparison between the band gap values, the averaged phonon energies and the electron-phonon coupling strengths of the different polymorphs using the same experimental technique. We provide an experimental study to investigate the electronic bandgap transitions in monoclinic β−, orthorhombic κ−, rhombohedral α−, defective-spinel γ- and cubic bixbyite δ−Ga2O3 as a function of the sample temperature. Temperature-dependent UV photoluminescence excitation (PLE) spectroscopy is employed in the temperature range between 5 K and 300 K and the temperature dependencies are discussed regarding the energy bandgap, the effects of electron-phonon coupling and the averaged phonon energies.
Keywords: Gallium oxide; bandgap; transition; spectroscopy; Photoluminescence excitation (PLE)