Field effect studies on metal-insulator-semiconductor structures of PbTe films

Abstract DC conductivity and Hall coefficient measurements have been performed on MIS structures of thin films of p-type PbTe grown on mica and glass, as a function of gate field and temperature. The films grown on mica were epitaxial and the effect of a negative gate field was found to decrease the Hall coefficient, Hall mobility and the defect scattering mobility. The effect of a positive gate field was opposite and less significant. On the other hand, the films grown on glass were polycrystalline and the mobility of the charge carriers was an order less than the value for epitaxial films. The dominant scattering mechanism in these films is the grain boundary potential barrier. The effect of a negative gate field has been observed to decrease the grain boundary potential barrier and to increase the Hall mobility. These results have been explained on the basis of accumulation and depletion of charges, induced by the field at the surfaces.