Energy spectrum of charge carriers in Ag2Te

Abstract

Conductivity σ(T) and Hall constant R(B, T) are studied for Ag2Te with excess 0.1% of Te. The change in the R sign from (−) to (+) is found in dependences R(B) at various temperatures. In the temperature dependences of R in a range of 1–3 kG, two extrema are found, namely, minimum at T ∼ 60 and maximum at T ≈ 80 K, and at B ≥ 5 kG, the double change in sign of R from (−) to (+) and from (+) to (−) is found. Temperatures of sign inversion for R depend on the magnetic field. At B = 15 kG, the sign of R varies from (−) to (+) at T ≈ 38 K, and from (+) to (−) at T ∼ 70 K. It is found approximately in the region of the change in the sign of R(T), the concentration n(T) and electrical conductivity pass through the minimum. It is established that the minima of n(T) and σ(T), extrema in R(T), and sign inversion for R(T) from (−) to (+) as well as the overestimated temperature dependence n∞T4 are caused by localization of conduction electrons at acceptor levels entering the conduction band of Ag2Te. The values of parameters of electrons (n, μn) and holes (p, μp) at the points of the change in the sign of R(T) from (−) to (+) and from (+) to (−) are determined.