The applicability of simple band models for the description of a pseudo-IV-VI semiconductor: TlBiTe2

Abstract

TlBiTe2, referred to as pseudo-PbTe, is of great technological interest. From the study of different samples in the plasma region where the absorption of free carriers dominate, the concentration dependence of the susceptibility effective mass is obtained. The energy gap at room temperature is determined from electrical measurements. The authors examine the applicability of simple band models on the material. In the region of lower concentrations (<or=2*1020) the dependence of the effective mass on the concentration is in accordance with the Kane model and this fact suggests that the material is really a narrow band gap semiconductor. At higher concentrations the empirical model is suitable and this can be attributed to the occupation of a second much higher conductivity band. The Cohen model is not suitable for TlBiTe2.