Optical and Electrical Investigations of the Anisotropy of Sb2Te3 Single Crystals

On Sb2Te3 single crystals with conductivities between 3700 and 7000 Ω−1 cm−1 the anisotropy of the reflectivity of polarized infrared light, the anisotropy of conductivity and of the Seebeck and Hall coefficients are investigated. In addition to the excitation of free carriers in the reflection spectra of donor doped crystals also interband excitations are observed. In terms of a six‐valley band model with anisotropic scattering the contribution of the free carriers to the susceptibility is calculated, and the anisotropy ratio of the effective susceptibility masses magnified image is given. It is found that the anisotropy decreases with increasing conductivity. A comparison of magnified image with the anisotropy of conductivity σ ⊥c/σ‖c shows that for Sb2Te3 single crystals with σ‖σ ⊥c < < 5000 Ω−1 cm−1 the carrier scattering is anisotropic.