Study on the trap properties of nano-ZnO modified polyimide based on surface potential decay method

The space environment will charge the surface of the spacecraft. Due to the low discharge ability of the dielectric material, it may cause the surface discharge of the spacecraft and affect the normal work of the spacecraft. Polyimide is a typical dielectric material on the spacecraft, this paper attempts to improve the surface discharge ability by modifying polyimide with nano-ZnO. The research method is based on the surface potential decay platform, which is an intuitive approach to evaluate the states of surface charging. The surface potential decay characteristics of pure polyimide and its modified samples are tested. The surface potential decay mechanism of the dielectric is analyzed by calculating the trap characteristics. Results show that the surface potential of ZnO modified polyimide has less decrement and rate of decay than that of the pure polyimide. The deep trap density of electron trap and hole trap density is less than that of pure polyimide, the shallow trap of pure polyimide is the lowest. The change of electron trap level is small, while the hole trap level increases.