石墨烯包覆金属纳米线复合结构制备及电子输运性质

Metallic nanowires (NWs) can be used as quantum electronic wire in nanodevice,making it a promising candidate material for potential application in nano- and micro-electronic systems. However, due to their large specific surface area and high activity, metallic NWs are unstable at room temperature and easy to be oxidized, restricting their practical application of NWs significantly. So it is emergent to develop a effective method to form an inert coating shell around the NW. This project is aimed to explore a simple method, in which carbon-containing nickel (iron) nanowires are first grown on a nanograted surface by sputtering technique, then, a annealing method is used to make the carbon atoms diffuse to the surface and transform into stacked graphene layers around the nickel cores. This project also needs to obtain the best technological parameter to fabricate the shell /core composite structure. Final sample will be chanracterized by FESEM,X-ray diffractor and TG-DSC to observe its micro-morphology, to detect its phase composition and to analyze its thermodynamic stability. Molecular Dynamics simulation will also be performed to disclose the nucleation mechanism of the graphene, and to study the catalysis effect of the nickel (iron) on the graphene growth. A proper thermodynamic model will be proposed to study the thermodynamic condition and driving force in the graphene forming process. Study of the current amplification effect and negative differential resistance with high on/off ratio will provide the theoretical evidence for the design of novel nanowire transistor.

金属纳米线作为纳米器件的导线在微电子领域有广阔的应用前景,但金属纳米线表面积大、活性高，在常规环境下不稳定，易氧化断裂，严重影响其实际应用,如何在纳米线表面生成一保护性碳壳层是该领域亟待解决的问题。本项目拟利用混合溅射技术将Ni(Fe)-C合金沉积到具有光栅结构的硅衬底上形成Ni(Fe)-C合金纳米线，利用退火工艺使碳原子向纳米线表面扩散形成石墨烯，研发一种工艺简单，形貌和尺寸可控的石墨烯包覆金属纳米线复合结构制备方法，找出最佳工艺参数；利用场发射电镜、X射线衍射及TG-DSC等仪器观察样品的微观形貌、测试相结构及热力学稳定性；利用分子动力学模拟碳原子在纳米线表面的形核过程，揭示石墨烯形成过程中Ni和Fe的催化作用机理，提出热力学模型并探究石墨烯发生相变的条件及驱动力；研究该复合结构的电子输运性质，分析其产生电流放大效应及负微分电阻效应的原因，为设计开发新型纳米线晶体管提供理论依据。

制备常温环境下稳定、不易氧化断裂的金属纳米线作为纳米器件的导线在微电子领域有广阔的应用前景。本项目首先系统地研究了石墨烯包覆金属纳米线复合结构可行性，探索了利用对Ni-C合金退火制备“石墨烯包覆金属纳米线”复合结构的机理，找出了合适的材料制备工艺参数，包括碳浓度、退火温度、以及初始Ni-C合金的尺寸与形状，采用分子动力学模拟的手段揭示了石墨烯在金属表面的形核生长规律；还探讨了液态金属与石墨烯间的相互作用关系，找出了有效调控金属液滴行为的石墨烯表面结构，发现了石墨烯受限条件下液态金属的结构演变规律，为精确制备石墨烯-金属复合材料提供了理论基础；进而着重研究了石墨烯等碳纳米材料通过掺杂、拼接而成的复合结构和金属纳米线的电子输运性质，找出了产生电流放大效应及负微分电阻效应的原因，设计了多种性能优异的功能分子器件，可应用于晶体管、传感器、芯片、微型发射器等；最后研究了存在一定缺陷的石墨烯和金属纳米粒子的氧化机理，揭示了缺陷石墨烯的氧化演变规律，发现了金属链状氧化物结构，提出了一些抗氧化措施来保证石墨烯-金属纳米线复合结构的稳定。. 本项目的研究成果不仅提出了合适的工艺来制备石墨烯包覆金属纳米线复合结构，还系统地研究了多种碳纳米材料基复合结构的电学性质，对于制备功能纳米器件等新型微电子产品具有非常重要的理论指导意义。