基于铁电栅石墨烯晶体管的柔性存储器关键材料与机理研究

With the rapid development of flexible electronic technology, flexible nonvolatile memory shows a broad application prospects. Flexible nonvolatile memory based on organic field-effect transistors is still facing some problems such as slow write/read speed, high operating voltage, poor retention performance, low storage capacity,etc. Therefore, exploring new materials in the application of the flexible storage has important theoretical significance and application value. This project will employ graphene, which shows excellent characteristics in terms of high mobility, transparency, flexibility, low-cost and compatibility with flexible integrated circuits, combined with organic ferroelectric polymer P(VDF-TrFE) to prepare nonvolatile graphene-based field effect transistor (G-FET) memory on flexible substrate. We will establish and optimize the theoretical model of the transport properties in ferroelectric-gated G-FET, and thoroughly investigate the effect of ferroelectric polarization on carrier transport behavior in graphene and the memory performance. The device structure and process parameters will be simulated and optimized. The growth process of large area, continuous graphene films and the transfer method, as well as the preparation of high-performance P(VDF-TrFE) thin films will also be studied and further improved. We will also explore the interface characteristics between graphene and P(VDF-TrFE) film, and analyze the microscopic mechanism. Memory devices with excellent performance will be ultimately achieved, providing research examples and ways for the application of graphene in large-area, low-cost, flexible nonvolatile memory.

随着柔性电子技术的飞速发展，柔性存储器将具有广泛的应用前景。基于有机半导体材料的场效应晶体管柔性存储器目前还面临着读写速度慢、操作电压高、保持性能差、存储容量低等问题，因此探索新材料在柔性存储中的应用具有重要的理论意义和应用价值。本项目将利用石墨烯高迁移率、透明、柔性、低成本及可实现柔性集成的特点，结合有机铁电聚合物P(VDF-TrFE)，制备基于柔性衬底的石墨烯场效应晶体管（G-FET）存储器。建立并完善铁电栅G-FET器件的理论模型，深入理解铁电极化对石墨烯载流子输运行为的影响及其对存储效应的调控作用；模拟器件结构和工艺参数，并进行优化设计；研究并优化大面积、连续的石墨烯薄膜的生长和转移工艺以及高性能的P(VDF-TrFE)薄膜的制备工艺；探索石墨烯与铁电栅的界面特性，对其微观机制进行分析；最终获得性能优良的存储器件，为石墨烯在大面积、低成本的柔性存储器中的应用提供研究思路和实现途径。

本项目对基于石墨烯场效应晶体管(GFETs)的有机铁电双栅结构新型存储器进行研究，探索其在柔性存储应用中的关键科学问题。本项目从关键材料制备、器件结构设计、电学特性分析、存储机理研究以及柔性化关键技术等方面进行系统性的研究工作。首先，对关键性材料石墨烯的化学气相沉积(CVD)制备方法进行了研究，对所制备的石墨烯薄膜的品质、电导率、透过率等一系列物理特性进行了表征。在此基础上，设计并制备了GFETs，通过改变栅介质的类型和厚度等特征，获得石墨烯与栅介质间界面态特性对石墨烯中载流子输运行为的调控机制。进而将有机铁电P(VDF-TrFE)薄膜应用到GFETs中，以石墨烯作为沟道材料，设计并制备了具有双栅结构的有机铁电栅石墨烯场效应晶体管器件。针对有机铁电薄膜独特的制备工艺，设计并改进了有机铁电栅顶栅晶体管的制备工艺，探索了双栅调控下，石墨烯中载流子的输运特性，获得了有机铁电栅控下，石墨烯铁电存储器的存储机制和存储特性，并对其柔性化关键工艺技术进行研究，最终实现了柔性石墨烯存储器件，获得了较好的电学及存储特性。