An enhancement of a thermoelectric power factor in a Ga-doped ZnO system: A chemical compression by enlarged Ga solubility

Herein, we report a significant enhancement of the thermoelectric power factor in polycrystalline Ga-doped ZnO. Despite its higher carrier concentration, the Seebeck coefficient of Zn0.985Ga0.015O was larger than that of Zn0.990Ga0.010O benefiting from an enhancement of the density of states (DOS) effective mass. A gradual increase in the compressive stress with Ga substitution gave rise to a higher DOS at the bottom of the conduction band. An enlarged solution limit of Ga in the ZnO matrix due to a lower firing temperature accelerated the chemical compression. A single phase n-type Zn0.985Ga0.015O bulk exhibited a power factor of 12.5 μWcm−1 K−2.