Strong Electron-Phonon Coupling inβ-Ga2O3: A Huge Broadeningof Self-Trapped Exciton Emission and a Significant Red Shift of theDirect Bandgap

The temperature dependence of self-trapped exciton (STE) emission and theoptical absorption edge of monoclinic gallium oxide (beta-Ga2O3) has been carefully studied.According to this research, it is found that as temperature increases (from 10 to 300 K), theSTE and the direct bandgap of beta-Ga2O3exhibit a huge broadening (similar to 120 meV) and asignificant red shift (similar to 250 meV), respectively. Combined with theoretical analysis, thesetemperature-dependent change trends are found related to the strong electron-phononcoupling (EPC) effect in crystal, which is caused by the high localization (i.e., self-trapping) ofcarriers in beta-Ga2O3. Thisfinding further indicates that in the transition process of carriers'absorbing and releasing photons, the influence of lattice vibration needs to be considered anddescribed by the configuration coordinate model. The strength of EPC can be measured by theHuang-Rhys factor, which is aboutS approximate to 9 for beta-Ga2O3with the polar longitudinal opticalphonon mode of lower energy (similar to 31 meV) being involved.

Automated summary

This study carefully investigates the temperature dependence of self-trapped exciton emission and optical absorption edge in monoclinic gallium oxide. The results show that with increasing temperature, both the self-trapped exciton and the direct bandgap exhibit significant broadening and red shift. These temperature-dependent changes are attributed to the strong electron-phonon coupling effect caused by the high localization of carriers in the crystal. This finding emphasizes the importance of considering lattice vibrations in the process of carrier absorption and photon release.