低能团簇离子注入制备宽禁带氟化石墨烯(fluorographene)

Fluorographene is a semiconductor with wide and tunable bandgaps (0-3.13 eV), which is promising for application in graphene-based electronics and optoelectronics. However, some basic physical properties are yet to be determined and clarified, for example, some work found a much wider bandgap (3.8 eV) for fully fluorated graphene. This project aims to generation of F1-F10 cluster ion beams by using the cesium sputtering ion source of the injector of a 1.7 MV tandetron accelerator. The cluster ion beams will then be decelerated by electrostatic field down to ultra-low energies of 10-100 eV/atom and will be implanted (deposited) onto graphene, forming a fluorographene layer. The structure, composition (degree of fluoration) and morphology of the fluorographene layer will be measured by Raman scattering, XPS, HRTEM, STEM, and AFM, and the bandgap will be measured by photoluminescence spectroscopy. The number of fluorine atoms binding the carbon atoms of graphene can be precisely controlled by taking advantage of the controllability of the cluster size, ion energy and implantation dosage. This will enable establishment of the relationship of the bandgap with the process parameters, which will be used to optimize the process for fabrication of fluorographene with desired bandgap and other important parameters, laying the scientific foundation for ion beam synthesis of graphene-based optoelectronic materials.

氟化石墨烯(fluorographene, FG)是带隙可调的宽禁带半导体，是研制石墨烯光电子器件和光子学器件的重要基础材料，但是，FG的最大带隙（3.07eV,3.13eV或3.8eV）等基本物理性质仍待确定或澄清。本项目用串列加速器的铯溅射离子源产生氟团簇(F1-F10)负离子束，用静电场对团簇离子束进行减速，获得10-100eV/atom的超低能离子束，注入到graphene中，形成氟化石墨烯。用Raman光谱、HRTEM、XPS、AFM等方法测定其结构、成分和表面形貌，用光致发光谱和NEXAFS测定其光学性质和禁带宽度。利用离子束的能量、剂量精确可控的优势，精确控制沉积于石墨烯的氟原子数目以及石墨烯的氟化度。建立氟化石墨烯禁带宽度随团簇离子尺寸、离子能量、注入剂量变化的关系，摸索出团簇离子注入形成氟化石墨烯的最优化工艺条件，为离子束制备石墨烯发光材料提供科学依据。

氟化石墨烯(fluorographene, FG)是带隙可调的宽禁带半导体，是研制石墨烯光电子器件和光子学器件的重要基础材料，但是，FG的最大带隙（3.07eV,3.13eV或3.8eV）等基本物理性质仍待确定或澄清。本项目用串列加速器的铯溅射离子源产生氟团簇(F1-F10)负离子束，用静电场对团簇离子束进行减速，获得10-100eV/atom的超低能离子束，注入到graphene中，形成氟化石墨烯。利用离子束的能量、剂量精确可控的优势，精确控制沉积于石墨烯的氟原子数目以及石墨烯的氟化度。建立氟化石墨烯禁带宽度随团簇离子尺寸、离子能量、注入剂量变化的关系，摸索出团簇离子注入形成氟化石墨烯的最优化工艺条件，为离子束制备石墨烯发光材料提供科学依据。. 在串列加速器铯溅射离子源上，用硼靶、石墨靶、LiF靶进行了团簇离子束引出实验，引出了硼团簇B1~B8、C1~C10和氟团簇F1~F10的负离子束，以及LimFn分子团簇，束流强度在几个纳安至数十微安级（因团簇种类和尺寸而异），用上述团簇开展了离子注入单晶硅和过渡金属（Ni, Cu）的实验。其中硼离子注入得到了结深为15nm的硅基超浅结，得到二次离子质谱的证实。碳团簇离子注入得到了单层~少层石墨烯，并进行了氩、氧、氟等离子体刻蚀处理，在绝缘衬底表面得到了少层石墨烯。氟注入石墨烯得到了氟化石墨烯纳米片。. 在本项目支持下，与俄罗斯科学院微电子所、韩国东国大学合作开展了二维材料的制备和基于二维异质结的阻性存储器研究，在Au/MoS2/graphene异质结上观察清晰的I-V回线，发现该异质结具有电阻相差甚大的高阻态和低阻态，而在可见光照射时，器件出现具有新的阻态的I-V回线，与暗条件下的阻态一起形成四个阻态，显示出二维材料在多比特阻性存储领域具有潜在的应用前景。