Thermoelectric properties of defect chalcopyrites

The electronic structure and transport properties of the XIn2Te4 (X=Zn, Cd) compounds using the full potential linearized augmented plane-wave (FP-LAPW) method and the semi-classical Boltzmann theory are presented in this paper. The ternary chalcogenides ZnIn2Te4 and CdIn2Te4 are direct band gap semiconductors with a band gap of 1.08 and 1.03 eV respectively. Although the optical properties are very similar, the transport properties of these chalcopyrites differ. From the calculated Hall coefficient, it is found that the tellurides are p-type materials with electron concentration of 8.09×1019 and 4.80×1019 cm-3 respectively. The figure of merit shows variation with temperature in CdIn2Te4, whereas it is nearly constant over the entire temperature range (10-800 K) in ZnIn2Te4.