The role of the internal field on the electronic transport in insulators

The contribution of electric fields internally generated in insulating compounds to electronic conduction processes is considered. Analytical relations for interpreting the current-voltage-temperature characteristics are obtained when the field-assisted thermal ionization takes place. The cases of isotropic emission and electron emission parallel to the applied field, are considered. The evaluation of the thermal activation energy and of the Poole-Frenkel constant are in agreement with the theory and are similar to those obtained with other procedures. For tunneling the inclusion of internal fields leads to a resistivity dependence on the applied voltage and on the temperature, which is similar to that of hopping conduction. The average internal electric field amplitude is, in both cases, of the same order of magnitude as was estimated by other authors