Poole‐frenkel conduction in insulators of large impurity densities

Abstract

Electrical conduction due to thermal activation of electrons from impurity sites is studied in the case of amorphous insulating films of large impurity densities. Considering a two‐centre model the central barrier is assumed to be the current‐limiting one in the whole field range for the investigation of the influence of overlapping coulombic potential fields on the Poole‐Frenkel effect. The obtained current‐voltage characteristic contains an ohmic region at low fields and becomes similar to the Poole‐Frenkel effect at high fields. Interpreting experimental results on polytetrafluorethylene films in terms of this theory, it is possible not only to obtain consistent agreement with experiment but also to explain the better linearity in the plot of lg j vs. E1/2 than in the plot of lg (j/E) vs. E1/2. Copyright © 1974 WILEY‐VCH Verlag GmbH & Co. KGaA