A modified thermally stimulated current analysis method for direct determination of trap energy distribution

Abstract

A modified method is proposed to directly determine the trap energy distribution in dielectrics after high electric field charge injection based on thermally stimulated current (TSC) measurement. Firstly, through a series of equation derivation, it is found that obtaining trap energy distribution from measured TSC data becomes solving a nonnegative least squares problem. Then, an iteration algorithm is introduced to solve the problem in detail. Finally, the modified method is applied to analyze TSC experiment results of polyethylene terephthalate (PET) film, which are compared with other researchers' work. The experiment results show that there is a wide apparent peak in TSC curves, extending from ~325 K to ~400 K. After analyzing with the method, the peak is composed of two components formed by released charges previously trapped in the traps of two major depths of ~1.09 eV and ~1.18 eV in the range of 0.5-1.3 eV. Altogether, these results generally agree with other researchers' analysis of PET, which acquired by various measurements and methods. Moreover, in order to check the reliability of the algorithm, R-square values are calculated. The values are close to 1 which manifests that the numerical solutions are almost coincide with experiment data and the method is proved to be trustworthy, realistic and stable.