Effect of Sulfur Vacancies on the Thermoelectric Properties of Galena

Abstract

Dependences of Seebeck coefficient S, resistivity ρ, and thermal conductivity κ of narrow-gap PbS_1 –y (0 ≤ y ≤ 10⁻³) semiconductor crystals are studied at a temperature of Т = 305 K. It is found via EPR and the Hall approach that the number of sulfur vacancies and vacancy clusters grows along with nonstoichiometry parameter y of PbS_1 − y samples. Analysis of dependences S(y), ρ(y), and κ(y) shows that the sulfur vacancies and vacancy clusters form resonance levels in the conduction band of the PbS_1 − y crystals that affect their thermoelectric figure of merit.