Electrical properties of ZnO Nano-particles embedded in polyimide

The ZnO nano-particles were made in the polyimide dielectric matrix by using the chemical reaction between the zinc metal film and polyamic acid. The concentration of the ZnO particle is about 1.5×1012 cm−2, with average size below 10 nm, and its shapes are almost spherical. Then, the polyimide layer is a stable dielectric material with a dielectric constant of 2.9. To investigate the electrical properties of ZnO particles in the polyimide insulator film, we fabricated a metal-insulator-semiconductor (MIS) structure and measured capacitance-voltage (C-V) with temperature modulation. At room temperature, C-V hysteresis with a voltage gap of 2.8 V appeared in the MIS structure using SiO2/Si substrate. As the measuring temperature decreased, the C-V curves were shifted slightly to the accumulation region with gate bias. It was considered that the electrical charging may occur dominantly in nanoparticles, having only a few defects at the interface of the polyimide/SiO2 and the polyimide/ZnO.