Effect of chemical doping on the thermoelectric properties of FeGa3

Abstract

Thermoelectric properties of the chemically-doped intermetallic narrow-band semiconductor FeGa3 are reported. The parent compound shows semiconductor-like behavior with a small bandgap (Eg = 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 (S2/ρ = 62 μW/m K2) was observed for Fe0.99Co0.01(Ga0.997Ge0.003)3, and its corresponding figure of merit (ZT = 1.3 × 10−2) at 390 K improved by over a factor of 5 from the pure material.