Comprehensive Spectroscopic Study of Competing Recombination Channels and Thermal Quenching Mechanisms in β-Ga2O3 Single Crystals

This work investigates a comprehensive temperature-dependent photoluminescence study (7–300 K) of β- Ga2O3 single crystals under 250 nm excitation. The emission consists of three competing bands at ~3.55 eV (J1), ~3.37 eV (J2), and ~3.07 eV (J3). With increasing temperature, the spectra exhibit a redshift, band broadening, and a characteristic crossover near ~140 K. A two-channel Arrhenius analysis of global thermal quenching at λmax, J1 and J2, reveals a common shallow barrier E1 =7–12 meV alongside deeper, band-specific barriers of E2=27 meV for J1 and E2=125 meV for J2. The J3 band shows a non-monotonic intensity (dip–peak–quench), reproduced by a trap-assisted generation term with a carrier-release energy Erel of order tens of meV, explaining a local maximum around ~170 K. Linewidth analysis using a single-optical-phonon model yields effective phonon energies Eph≈40–46 meV for the integral spectrum and J3, consistent with strong electron–phonon coupling; deviations for J1/J2 indicate multi-phonon and/or inhomogeneous broadening. These results establish a coherent picture of thermally driven redistribution from near-edge/STE-like states to deeper defect centers, modulated by shallow traps, and provide quantitative targets (activation and phonon energies) for defect engineering in β-Ga2O3-based optoelectronic and scintillation applications.