Temperature Dependence of X-Ray-Induced Photoconductivity in Kapton and Teflon

We have measured the X-ray-induced photoconductivity in Kapton (Dupont polyimide) and Teflon over the temperature range 100-5000K. The observed temperature dependence of the photoconductivity was strikingly different for these two materials. The qualitative behavior of the Kapton samples was consistent with the predictions of a model where the delayed photoconductivity signal is due to thermal release of trapped charge. In the case of the Teflon samples, the observed prompt conductivity was almost temperature independent and we observed a pronounced peak in the delayed component of the photoconductivity at about 360°K. The decay time of the delayed photoconductivity for Teflon was also observed to be temperature dependent. We discuss changes in the occupation of deep trapping levels as a possible mechanism for the observed thermal quenching of the Teflon photoconductivity.