Field stimulated interfacial electron transfer

The time dependence of the charging of insulators on contact with metal electrodes has been examined by determination of the charge after both multiple repeated contacts and time-varying, single contact as well as measuring the influence of applied fields in the charge transfer process. The practical aspects of these investigations have been exhibited by showing that microphony in polymer insulated structures is well described by stored charge effects and further, that injected charges may contribute significantly to the so-called piezo-electric effect in polymers. All the experimental data are described by a logarithmic dependence of the charge density ¿¿ on time. A simplified analysis indicates that the field (E) dependence of the rate of charge increase is described by an expression of the form ¿¿ = KE1/2 In t. It is concluded that the charge transfer process is consistent with a self-field limited injection mechanism but greater refinement is necessary in both experiment and theory to permit its unequivocal specification.