Carrier Concentration–Dependent Seebeck Coefficient in β‐Ga₂O₃

β‐Ga 2 O 3 is an ultrawide‐bandgap semiconductor whose thermal stability makes it a potentially interesting candidate for high‐temperature thermoelectric applications. In this work, the experimental relation between the room‐temperature (RT) Hall electron density ( n ) and the RT Seebeck coefficient ( S ) for β‐Ga 2 O 3 ( n from 8 × 10 16 to 4 × 10 19 cm −3 ) is provided. The use of high‐structural‐quality 1) melt‐grown single‐crystal wafers and 2) Si‐doped homoepitaxial layers allows to minimize the effect of structural defects. The experimental Seebeck coefficients are located between the modeled S ( n ) relation for ionized impurity scattering and polar optical phonon scattering mechanism. The S ( n ) data reported in this work can serve as a “calibration curve” for the estimation of volume electron concentrations from simple Seebeck coefficient measurements. Combining our data with the measured electrical conductivity and thermal conductivity values from the literature, the thermoelectric power factor and figure of merit ZT are calculated. These results suggest the maximum of ZT to be found at electron concentrations above 4 × 10 19 cm −3 at RT.