Effect of chemical doping on the thermoelectric properties of FeGa_3

摘要

Thermoelectric properties of the chemically-doped intermetallic narrow-band semiconductor FeGa_3 are reported. The parent compound shows semiconductor-like behavior with a small bandgap (E_g = 0.2 eV), a carrier density of ～1018 cm~(-3), and a large n-type Seebeck coefficient (S ～ —400 μV/K) at room temperature. Hall effect measurements indicate that chemical doping significantly increases the carrier density, resulting in a metallic state, while the Seebeck coefficient still remains fairly large (～- 150 μV/K). The largest power factor (S~2/ρ = 62 μW/m K~2) was observed for Fe_(0.99)Co_(0.003)3,(Ga_(0.997)Ge_(0.003))3, and its corresponding figure of merit (ZT= 1.3 x 10~(-2)) at 390 K improved by over a factor of 5 from the pure material.