关联电子氧化物Mott金属-绝缘体相变的电场调控及器件应用

With the scaling of silicon field effect transistors (FETs) approaching physical limit. Correlated electron oxides (CEOs) have attracted increasing attention because of their rich physical phenomena. Based on Mott metal-insulator transition of CEOs, Mott transistors is believed to have advantages over silicon FETs in terms of no scaling limit, greater functionality, higher speed and lower energy consumption. Thus, the Mott transistor has been regarded as one of the most promising candidates for "Beyond CMOS" next generation FETs. However, the present Mott transistors are facing low ON/OFF ratio and the problems in stability and integration due to the liquid form of ionic liquid gate dielectric. To solve these problems, we propose a new route to design a Mott transistor based on a shift of Mott transition by electric field and use "solid" ion gels as gate dielectric. According to this new idea, SmNiO3 and VO2 are selected as the study objects because their Mott transitions show sharp resistance change above room temperature. With huge carrier modulation of electric double layer formed at the interface between ion gels and CEOs, the tuning of Mott transition by electric field will be conducted. We will investigate the effect of electrostatic carrier doping on carrier localization and structure of CEOs and reveal the mechanism of Mott transition controlled by electric filed. This research will shed some new light on fabrication of novel high-performance Mott transistors.

随着硅晶体管尺寸逐渐达到其物理极限，人们开始把目光转向具有更加丰富物理现象的关联电子氧化物。基于关联电子氧化物Mott金属-绝缘体相变的新型Mott晶体管被认为没有物理极限，而且具有多功能、高速和低功耗等优点，成为"Beyond CMOS"新一代场效应晶体管有力的竞争者。针对目前Mott晶体管器件开关比不高、离子液体栅极电介质不稳定、集成度差等问题，本项目提出基于电场对Mott相变移动的调控、以"固态"离子凝胶为栅极电介质研制Mott晶体管的新思路。以室温上具有电阻突变特性的SmNiO3和VO2为研究对象，利用双电层结构巨大的载流子调控能力，开展电场对其Mott相变的调控研究，揭示静电场注入的载流子对关联电子氧化物的载流子局域化和晶体结构的影响规律，阐明Mott相变电场调控的机制，为开发具有自主知识产权的、高开关比、低能耗和高稳定性的"全固态"双电层Mott晶体管进行积极探索。

双电层晶体管（EDLT）结构是调控界面新奇物性强有力的技术手段，同时也为新原理器件的研制带来了新的机遇。本项目采用脉冲激光沉积法制备出高质量关联电子氧化物（镍氧化物、铱氧化物和VO2）薄膜，总结了生长工艺、外延应力以及化学掺杂对氧化物薄膜Mott金属-绝缘体相变的影响规律。利用双电层结构巨大的载流子调控能力，实现电场对关联电子氧化物Mott相变的调控，揭示电场调控Mott相变的机制。开发出具有自主知识产权的、高开关比、低能耗和高稳定性的“全固态”双电层Mott晶体管。目前已在Journal Materials Chemistry C、Scientific Reports、Journal of Physics D: Applied Physics等核心刊物上发表SCI论文12篇。主要研究成果如下：.1）本项目通过设计合理的双电层晶体管EDLT原型器件，实现对SmNiO3薄膜MI相变的静电场调控，通过仅2V电压的施加，就可将薄膜的MI相变调控至室温下，并具有良好的可逆性。.2）成功在具有机械柔韧性的云母片衬底上制备出了VO2薄膜，以离子凝胶为介电层研制出“全固态”双电层Mott晶体管器件，实现了离子凝胶对VO2相变的调控，并伴随30%的红外透射率的变化，为柔性氧化物薄膜与器件的研制提供重要的理论基础和实验依据。.3）基于特殊Mott绝缘体特性，Sr2IrO4 -EDLT器件在2.5 V的外加电压下，实现了具备双向、总开关比达到4个数量级以上的阻变效应。基于这一阻变效应，实现了后膜电流的指数衰减、双脉冲易化、增强-抑制等神经突触特性的模拟。