Preparation And Device Application Of Flexible Inorganic Composite Ferroelectric Thin Film

Due to the excellent ferroelectric,piezoelectric and pyroelectric properties,lead-based ferroelectric materials such as lead zirconate titanate(PZT)and lead magnesium niobate-lead titanate(PMN-PT)have been used in a wide range of devices such as micro-electromechanical systems(MEMS),sensors,drivers,etc.The new concept for thinner devices have put forward new requirements and challenges on the performance,stability,integration and process compatibility of ferroelectric thin films.At present,the one-step growth process,structureactivity relationship,device structure and stability of flexible ferroelectric thin films are still inevitable problems in the process of device application of ferroelectric materials.Therefore,this article mainly focuses on the two ferroelectric materials of lead zirconate titanate and lead magnesium niobate-lead titanate,and explore the thin film fabrication process of ferroelectric materials on flexible substrates by pulsed laser deposition.Meanwhile,applied composite structure to achieve performance improvement and optimization,and finally explored the mechanism of performance improvement,which provided a basis for subsequent device structure design.Therefore,the process and device applications of the flexible inorganic composite film in this article can be divided into the following two section:(1)Research on the preparation process of PZT and PMN-PT monolayer films on different substrates.PZT and PMN-PT were deposited on STO and two-dimensional flexible mica substrates.At the same time,reflection high-energy electron diffraction(RHEED)was used to analyze the deposition kinetics of the bottom electrode layer on the substrate,the effect of the bottom electrode layer on the growth of ferroelectric thin films was explored.In the meanwhile,the process parameters of each layer of PLD deposition were optimized,and the influence of the substrate and electrode structure on the performance of the single-layer film was clearfied with the analysis of leakage current and polarization characteristics.(2)Research on the mechanism of flexible composite film preparation and performance improvement.Analysis of the improvement of ferroelectric properties of composited films were carried out combined with the deposition sequences,leadage current density and dielectric as well as piezoelectric and ferroelectric test.And final we fabricated flexible devices which can maintain 80% of the polarization strength under bending stress and ferroelectric domain switching.And this kind of improvement can be explained by effective capacitance theory combined with fatigue and stability tests.In summary,this article focuses on the preparation process,device interface characteristics,macroscopic properties and fatigue characteristics of flexible inorganic composite ferroelectric thin films,and provides certain guidance for the thin film and device applications of highperformance ferroelectric materials.