Thermoelectric Properties of PbTe Crystals and Thin Films

The influence of Bi, introduced in the elementary form in the stoichiometric lead telluride, on the thermoelectric properties of PbTe crystals and thin films prepared by thermal evaporation in vacuum and deposition onto mica substrates was studied. The temperature dependences of the Hall coefficient, the Seebeck coefficient, electrical conductivity, charge carrier concentration, and charge carrier mobility were obtained in the range 77-300 K for the crystals and thin films. On the basis of them, the dependences of the properties on Bi concentration at fixed temperatures were plotted. The isotherms of the properties have non-monotonic character, which is attributed to the complex processes of the defect formation, taking place under introduction of the elementary Bi in PbTe. The behavior of the isotherms of the properties practically does not change with changing temperature. The correlation between Bi concentration in PbTe charge and the thermoelectric properties of the thin films was established, which gives the possibility to control thermoelectric properties of thin films by changing the charge composition. The Bi concentrations corresponding to the maximum values of thermoelectric power factor of the crystals and thin films were determined.