An Effective Method for Improving the Insulating Property of Polyvinyl Alcohol in Device with Supercritical Fluids

In this paper, we applied a supercritical fluids technology to improve the insulating property of polyvinyl alcohol film in devices. Polyvinyl alcohol film has some defects due to the process, which leads to some small molecules residues. Supercritical CO
₂
fluids have high solubility for small molecules. It can take the residual small byproducts molecules in polyvinyl alcohol synthesis process out of the film as well as passivating the dangling bonds, eliminating the defects in polyvinyl alcohol film and improve the insulating property. For investigation, polyvinyl alcohol was used as the dielectric layer to make metal-insulator-metal devices. After supercrical CO
₂
fluids treatment, the leakage current of devices reduces about 100 times. Through current fitting, we find that the electrical conduction mechanism has been changed from Hopping mechanism to Schottky emission mechanism. The FTIR result of the polyvinyl alcohol film has assisted to prove that the bondings in the film have changed after supercrical CO
₂
fluids treatment. Polyvinyl alcohol is an environmentally friendly material and, in this paper, supercrical CO
₂
fluids treatment took the small biotoxic molecules out and no biotoxic components were used in all processes. Therefore, this improvement technology can remove the preparation defects in the application of PVA in biological affinity devices.