Investigation of the Seebeck coefficient in ultra-wide bandgap materials presents a challenge in measurements; nevertheless, it is essential for understanding fundamental transport mechanisms involved in electrical and thermal conduction. β-Ga2O3 is a strategic material for high-power optoelectronic applications. The present work reports the Seebeck coefficient measurement for single crystal Sn-doped β-Ga2O3 in a wide temperature range (80–630 K). The non-monotonic trend with large magnitude and a negative sign in the entire temperature range shows that electrons are dominant carriers. The structural and Raman characterization confirms the single-phase and the presence of low-, mid-, and high-frequency phonon modes, respectively. The temperature-dependent (90–350 K) Hall effect measurement was carried out as a supplementary study. Hall mobility showed that μ ∝ T1.12 for T < 135 K and μ ∝ T0.70 for T > 220 K. Activation energies from the Seebeck coefficient and conductivity analysis revealed the presence of interband conduction due to impurity defects. The room temperature Seebeck coefficient, power factor, and thermal conductivity were found to be 68.57 ± 1.27 μV/K, 0.15 ± 0.04 μW/K2 cm, and 14.2 ± 0.6 W/mK, respectively. The value of the figure of merit for β-Ga2O3 was found to be ∼ 0.01 (300 K).

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