| In varied polymers, the comprehensive performance of polyimide is better than others, and it has been widely used in high-tech fields, as aerospace, microelectronics technology, et al. Aging and breakdown can occur in polyimide under long-term electric stressing due to space charge behavior. Charge storage and transport is decided by trap characteristics, so it is significant for improving polymer material properties through researching structure and distribution of trap.Photo-stimulated discharge (PSD) is an effective tool to study structure of trap, the storage and transport of charge in polymer. It is an isothermal measurement process. The PSD measurement is no damage. Deep trsps can be researched by this method. The paper described experimental system detailedly, verified stability and reliadility. The results showed that the measurement device meet experimental requirements well.PSDs in PI-100HN and PI-100CR film were tested under no charged, different injection time and different injection voltage, and multiple scans. The measurement results were shown that the distribution of trap levels in two types film is banded, 3.1eV-4.2eV for PI-100HN, 3.1eV-4.3eV for PI-100CR; the current increased when the injection time increased, peaks moved to the shortwave when injection time was increased from 60min to 90min, it showed that the injection charge was captured by shallow trap, and then some of trapped charge moved to the relative deeper trap with new injection charge under electric field; the current increased when the injection voltage increased. In addition, the aging and breakdown mechanisms in PI were analysed, it was found out that the broken was occurred in detrapping process. |
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