抄録
In this paper, the breakdown characteristics of polysiloxaneimide thin films which is applicable for cryogenic temperature were measured by taking advantage of self-healing breakdown in a wide temperature range. The effect of electrode metal and the effect of polarity reversal on the breakdown was also studied and the breakdown mechanism was discussed. The electric breakdown strength (Fb) was almost independent of temperature from 77K to room temperature and decreased with temperature in the high temperature region. It showed little electrode metal dependence at 77K, and was about 2.3MV/cm. When the polarity reversal experiment was carried out, Fb kept almost the same level after the polarity reversal at 77K. From these results, an electronic breakdown process was considered as a possible breakdown mechanism in the cryogenic region where only a limited electronic carrier injection from an electrode, and thus the formation of a space charge, were hardly expected. Al cathode gave lower Fb than Au cathode at room temperature and it fell just after polarity reversal and then gradually increased with the number of breakdowns. As a possible process concerning the Fb drop just after the polarity reversal, the possibility of the propagating breakdown (incomplete breakdown not inherent to the material) was checked. When we examined the breakdown hole of a sample surface under a microscope, however they were almost all the single-hole breakdowns, which are inherent breakdown of the material. The breakdown mechanism at room temperature seems to be associated with space charge formation.
