Anomalous temperature dependence of thermoelectric power of PbTe thin films

TLDR: In this paper, thin films of thicknesses ranging from 400 to 4000 A have been prepared by vacuum evaporation at a pressure of 5×10−5 Torr on clean glass substrates held at room temperature.

Abstract: PbTe thin films of thicknesses ranging from 400 to 4000 A have been prepared by vacuum evaporation at a pressure of 5×10−5 Torr on clean glass substrates held at room temperature. The thermoelectromotive force of these films has been measured in the temperature range 300–600 K. It is found that thermoelectric power, SF varies anomalously with temperature, being constant at lower temperatures, and rapidly decreasing at higher temperatures. SF is found to be positive indicating that the samples are p type. The anomalous behavior is explained by assuming that at higher temperatures additional donor levels are generated due to creation and ionization of defects in the system.