Effect of Annealing on the Electrical Conductivity and Thermoelectric Power of PbTe, SnTe, and Pb_0.75Sn_0.25Te Crystals

PbTe, SnTe, and Pb_0.75Sn_0.25Te single crystals have been grown and their electrical conductivity and thermoelectric power have been measured in the range 90–300 K before and after annealing. The results demonstrate that the conductivity of unannealed PbTe and Pb_0.75Sn_0.25Te crystals, its variation with temperature, and its type are determined mainly by structural defects formed during crystal growth and sample preparation, which can be eliminated by annealing. The electrical properties of unannealed and annealed SnTe crystals are determined mainly by acceptor vacancies on the tin site, whose concentration reaches 10²⁰ to 10²¹ cm^–3.