低压操作有机半导体/铁电复合阻变存储结构的研制及性能优化研究

Organic semiconducting/ferroelectric blend resistive films well solved the cross-talk problem existing in traditional resistive devices and thus attracted more and more attention in recent years. In blend films both semiconducting and ferroelectric phases formed phase separation structure with discrete semiconducting filaments, which connected with both electrodes, surrounded by continuous ferroelectric phase. Polarization states in ferroelectric phase modulated the conductivity of semiconducting filaments, as contributed to the resistive property. To meet the requirements of high performance, low consumption and low voltage operation for development of new electronic devices, the thickness of these blend films should be, for example, less than 100nm. However, with the decrease of film thickness, leakage current became obvious and crystallinity and ferroelectricity in ferroelectric phase also degraded, both of which resulted in the deterioration and even failure of resistive performance in such blend films. Here the proposer put forward this proposal for development and optimization of low-voltage-operated and high-performance semiconducting/ferroelectric blend resistive devices. To realize this goal, it is expected to develop removable PTFE-template-based epitaxial growth method for organic films. Via the precise selection of organic semiconducting materials and also the guidance of dissipative particle dynamics simulation, optimization of fabrication process and parameters of semiconducting/ferroelectric blend films is realized. Based on all these work, integration of both PTFE-based epitaxy method and optimized fabrication technique of such blend films is expected in order to realize the high efficient fabrication of low-voltage-operated and high-performance blend resistive films.

有机半导体/铁电复合阻变薄膜克服了传统阻变器件中存在的串扰问题，近年来受到越来越多的关注。复合薄膜中半导体相和铁电相形成相分离结构：离散的半导体相形成连通上下电极的导电细丝，嵌入在连续的铁电相网络中。铁电相的极化状态调制半导体相导电性，产生阻变存储特性。为满足高性能、低功耗、低压操作等新型电子器件开发的要求，复合薄膜厚度须减至100nm以下。然而，随着薄膜厚度降至纳米量级，薄膜漏电特性凸显，铁电相结晶度和铁电性劣化，最终导致半导体/铁电复合薄膜阻变性能退化甚至是失效。基于此，申请人提出本课题申请，旨在开发低压操作的高性能半导体/铁电复合阻变器件。为实现这一目标，拟开发基于可移除聚四氟乙烯模板的聚合物薄膜外延生长工艺；经由半导体材料的精准选择以及耗散粒子动力学模拟的指导，实现复合薄膜制备工艺参数优化；在此基础上，集成外延工艺和复合薄膜制备工艺，实现高性能、低压操作复合阻变薄膜的高效制备。

本课题旨在开发高性能、低压操作有机半导体/铁电复合阻变薄膜及器件。研究内容涉及空气稳定有机半导体材料的优选、基于可移除PTFE模板的铁电共聚物薄膜外延工艺优化及外延工艺与半导体/铁电复合阻变薄膜制造工艺的集成等。研究中系统优化了外延工艺参数(工作温度及压强)，获得明显改善的结晶度和铁电性能。选取具有高HOMO能级的F8T2作为半导体相来制备半导体/铁电[F8T2/P(VDF-TrFE)]复合阻变薄膜，获得明显改善的器件稳定性。经由PMMA掺杂，可进一步提升器件抗击穿、抗电疲劳特性。经由PMMA掺杂调控，实现了PMMA/F8T2/PVDF三元复合阻变薄膜，并经由纳米红外谱分析，确定了三元组分纳米尺度下的空间分布。经由外延工艺与复合阻变薄膜制备工艺集成及参数优化，光滑PTFE模板的二维限制作用更有效降低了复合薄膜的表面粗糙度，进而抑制了器件关态电流，整体提升器件性能。所制备半导体/铁电复合阻变薄膜的写入/擦除电压小于5V，读出电压1.5V，开关比10^5。