Energy spectrum of holes in Sb₂Te_2.9Se_0.1 solid solution according to the data on the transfer phenomena

Abstract

The temperature dependence of the Hall coefficient of a single crystal of the p-Sb₂Te_2.9Se_0.1 solid solution grown by the Czochralski technique is studied in the temperature range 77–450 K. The data on the Hall coefficient of the p-Sb₂Te_2.9Se_0.1 are analyzed in combination with the data on the Seebeck and Nernst–Ettingshausen effects and the electrical conductivity with allowance for interband scattering. From an analysis of the temperature dependences of the four kinetic coefficients, it follows that, at T < 200 K, the experimental data are qualitatively and quantitatively described in terms of the one-band model. At higher temperatures, a complex structure of the valence band and the participation of the second-kind additional carriers (heavy holes) in the kinetic phenomena should be taken into account. It is shown that the calculations of the temperature dependences of the Seebeck and Hall coefficients performed in the two-band model agree with the experimental data with inclusion of the interband scattering when using the following parameters: effective masses of the density of states of light holes m ^* _d1 ≈ 0.5m ₀ (m ₀ is the free electron mass) and heavy holes m ^* _d2 ≈ 1.4m ₀, the energy gap between the main and the additional extremes of the valence band ΔE _v ≈ 0.14 eV that is weakly dependent on temperature.