Doping of p-type ZnSb: Single parabolic band model and impurity band conduction

Even though the ZnSb compound has been known for decades and used in the earliest thermoelectric devices, the potential of the material as a modern thermoelectric may be underestimated. We synthesized p-type doped samples using ball-milling and hot-pressing and measured their thermoelectric properties including mobility and carrier concentration. Establishing a single parabolic band (SPB) model using these measurements on the Cu, Sn, and self-doped samples allows for predictions on the optimum thermoelectric efficiency. It is projected to reach zT = 0.75 at 700 K. Deviations from the SPB model at low carrier concentrations are discussed and impurity band conduction is brought in as a possible explanation.