The Development Of Flexible Ferroelectric Storage Structure And Characterization

Poly(vinylidene fluoride)(PVDF) and its copolymer with trifluoroethylene P(VDF-TrFE), have drawn much attention in recent years since they exhibit strong spontaneous polarization, excellent polarization stability and short switching time, as well as flexibility, compatibility and easy processing. Nonvolatile memory with ferroelectric polymer films have a good compatibility with the semiconductor integrated circuit processing, which has the advantage of flexibility, high storage density, low-cost, low power consumption, fast read-and-write, etc.. There are prospects for application and wide ranges of application markets.Based on the ferroelectric polymers, I prepared the flexible capacitor structure of ferroelectric thin films, the composite capacitor structure of ferroelectric/buffer layer, and the ferroelectric field effect transistor (FeFET). Then the morphology and electrical properties were respectively characterized to determine the impact of bending substrate on the ferroelectric film. The main contents include:1. The bending effect on electrical properties in capacitor structure of ferroelectric P(VDF-TrFE) films was studied. The electrical properties of thin films under different curvature bending were determined by means of Sawyer-Tower circuit. Then the ferroelectric hysteresis loops and switching curve were given to analyse the changes in the coercive field, remanent polarization, electrical retention, polarization fatigue and leakage property with the substrate bending.2. The electrical properties of the composite capacitor structure of ferroelectric/buffer layer were studied in the improved electrical properties. Under preparation of different thickness of the composite capacitor structure, the electrical properties of thin films were also determined by means of Sawyer-Tower circuit. The improvement of retention performance and leakage current were mainly compared and analyzed.3. The output and transfer characteristics of the ferroelectric field effect transistor (FeFET) were studied. The preparation of the field-effect transistor was based on the oxide semiconductor MOS structure with spin-coating processing of ferroelectric thin films. The storage performance and electrical stability of the storage structure were improved by optimizing the structure parameters. The output and transfer characteristics were test in order to study the the threshold voltage modulation of ferroelectric thin films, the semiconductor carrier mobility and device switch ratio.