Interrelation of Electronic Properties and Defect Equilibria in PbTe

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Abstract
The resistivity, Hall coefficient, and Seebeck coefficient of single crystals of PbTe were investigated in the range from 77° to 900°K using a capsuling arrangement which prevented tellurium loss from the specimens at elevated temperatures. The low temperature properties obtained agree with the data reported in the literature. The thermal energy gap obtained from the high temperature measurements cannot, however, be brought into agreement with the energy gap determined from room temperature absorption measurements by considering solely the excitation of electron‐hole pairs across the energy gap at elevated temperatures. Rather, it is necessary to include the carriers generated by defect formation at elevated temperatures. Both Schottky‐Wagner and Frenkel defects are present, the activation energies for formation of the two types of defects being related by the equation EF=½ES+0.55 ev≃0.7 ev.