2024/05/07 by Meißner, Moritz, Bernhardt, Nils, Nippert, Felix +3
#500 Naturwissenschaften und Mathematik::530 Physik::530 Physik #band gap #electronic band structure #excitons #gallium #optical properties #oxides #photoluminescence excitation spectroscopy #photoluminescence spectroscopy #polarization #spectroscopy
paper · doi:10.14279/depositonce-20462
The monoclinic beta-phase of gallium oxide possesses an ultra-wide bandgap that surpasses other wide bandgap materials such as SiC and GaN, making it a promising candidate for power electronic device technologies. We investigate the first fundamental optical transitions in this material, which exhibit a strong directional dependence. To determine the energies and orientations of these transitions, temperature-dependent and angular resolved photoluminescence excitation spectroscopy is applied. We observe a distinct excitation channel located energetically between those of the first two optical transitions Γ1−1 and Γ1−2. While previous absorption edge and reflectance spectroscopy studies have assigned a transition in this spectral range to either the Γ1−1 or the Γ1−2 transition, our findings demonstrate no pronounced polarization dependence of this excitation channel within the (010) plane, an observation not reflected in calculations of the band-to-band transitions in β-Ga2O3.