基于柔性衬底的石墨烯高频纳机电谐振器研究

High-frequency nano-electromechanical resonator on flexible substrate can be used to realize nano-scale,low power consumption electronic devices,such as high frequency osillator,ultra-high sensitivity sensor,and single molecular detector in non-plane applicatioin.It is especially useful in nowadays rapid developing applications ,like medical,bio-chemical,comsumer electronics,etc. However,the development of high-frequency nano-electromechanical resonator on flexible substrate is still no report yet.This is because the process of Nano-electromechanical systems (NEMS) is still not mature,the conventional thin film is not good enough for NEMS devices,and the actuator and detector method for NEMS is still not effective.In this project, we would like to use graphene instead of conventional thin film material, which has excellent performance in mechanical,electrical, and thermal properties .Based on double clamped nano-electromechanical resonator,we propose a novel fabrication process by using photodefinable polyimide precursor that can be patterned to cleanly resolve micron-scale patterns without the need of photoresist. This method can overcome the poor adhesion,hard to keeping flat, and easily deformation problems in flexible device fabrication.Moreover, to effectively actuate and readout, the electrical method based on resonant channel transistor(RCT) will be adopted. And an equivalent circuit model including mechanical-electric-thermal coupling is proposed to design device structure and optimize detection circuits, which will improve the amplitude of device response and increasing the sensitivity of detection system. The results of the project can pave the way for developing fully intergrated flexible thin film intergrated circuit(IC) by NEMS-IC monolithic intergration.

基于柔性衬底的高频纳机电谐振器可在非平面载体上实现高频振荡器、高灵敏度传感器和单分子检测器等，在医疗、消费电子等领域有着巨大的应用潜力。然而长期以来由于纳米电子薄膜材料机-电特性不理想、纳米器件工艺不成熟和缺乏高效激励与检测技术等关键原因，柔性纳机电谐振器目前还未见相关报道。针对上述关键问题，本课题选择同时具有优秀的机械性能、电性能和热性能的石墨烯作为薄膜材料，采用双端固支梁纳机电谐振器结构，提出了一种基于可光刻液态聚合物柔性衬底的器件制备方法，可有效解决固态柔性衬底在器件制备过程中存在的粘附性差、平整度难控制、高温处理易变形等问题。此外，为实现高效的激励与检测，拟采用基于谐振沟道晶体管(RCT)的全电学高频信号激励与检测方法，并通过建立力-电-热一体化等效电路模型进行器件结构和检测电路的优化设计，以提高器件响应幅度和系统的检测灵敏度。本项目的研究成果可加速高频柔性薄膜全集成电路的开发。

基于柔性衬底的高频纳机电谐振器可在非平面载体上实现高频振荡器、高灵敏度传感器和单分子检测器等，在医疗、消费电子等领域有着巨大的应用潜力。然而长期以来由于纳米电子薄膜材料机-电特性不理想、纳米器件工艺不成熟和缺乏高效激励与检测技术等关键原因，柔性纳机电谐振器目前还未见相关报道。针对上述关键问题，本课题针对具有优秀的机械性能、电性能和热性能的石墨烯作为薄膜材料，采用双端固支梁纳机电谐振器结构，提出了一种高质量金辅石墨烯助转移技术，在硅硬质衬底和柔性聚对苯二甲酸乙二酯类塑料（PET）衬底上开展了器件制备试验，验证了其可行性，开发了石墨烯纳机电谐振器；同时开展了基于柔性PET衬底上的石墨烯晶体管和柔性液晶聚合物衬底（LCP）的微波无源电路器件制备。实现了最高张力达5%、最高振荡频率大于28GHz（张力<2%时）的柔性石墨烯晶体管器件。揭示高频石墨烯纳机电谐振器在大形变条件下的场效应特性与机械振动规律，建立了能够准备预测NEMS的频率调谐、温度调谐和非线性特性等方面的高频等效电路模型，为后期结构优化和集成电路设计提供了重要的理论依据和设计工具。共发表SCI刊源期刊论文29篇和本学科A类会议IEEE IMS论文6篇，其中在本学科权威期刊IEEE Transactions on Microwave Theory and Techniques、IEEE Electron Device Letters和 IEEE Transactions on Electron Devices上9篇。授权国家发明专利3项，申请荷兰发明专利1项，培养博士后1名，博士生4名，硕士研究生5名。