The Influence of Weak Tin Doping on the Thermoelectric Properties of Zinc Antimonide

ZnSb would be a good thermoelectric material with carrier concentration above 10 19 /cm 3 , but unfortunately this has been shown to be difficult to achieve, particularly with Sn as a dopant. Two series ZnSb samples doped with Sn and ZnSn were prepared using hot-pressing technics, and their thermoelectric properties were investigated in the temperature range from 300 K to 700 K. The tin content of the samples was in the range from 0.1 to 0.5 at.%. Surprisingly, samples with lower tin content achieved higher carrier concentration, which is beneficial for thermoelectric performance. Samples doped with 0.1 at.% Sn achieved Hall carrier concentration above 1 × 10 19 /cm 3 , reaching ZT of 0.9, while for samples doped with 0.5 at.% Sn, the Hall carrier concentration was close to the hole concentration of pure ZnSb. Also, by analyzing hysteresis present in the heating–cooling cycles, we conclude that the role of intrinsic defects in ZnSb is important and that these defects clearly determine the ability of ZnSb to achieve ZT near 1.