Synthesis and functionality of nano-carbon thin films grown by surface precipitation

通过使用溶解的碳掺杂剂的表面沉淀来合成低维纳米碳是一种用于在没有外部碳源的情况下制造纳米碳的新颖方法（Fujita等人，2003，JJAP）。这就要求我们根据纳米碳的生长机理来控制纳米碳的变化。本研究的目的是利用表面纳米表征技术阐明碳掺杂金属基底上的生长机理，建立纳米碳的合成和控制方法，并探索其新的功能和应用。对于样品，各种碳掺杂金属（单晶C-Ni（111）、多晶C-Ni、C-Pt、C-Co等）在真空中在高温下通过固态扩散进行高达约0.3原子%的碳掺杂。抛光和清洗后的样品在超高真空下热处理，在基底上制备纳米碳膜，用扫描探针显微镜（SPM）和透射电镜（TEM）对纳米碳膜进行表征。 关于我们 三维扫描俄歇显微镜（SAM）。对于C-Ni（111），我们发现不同的热处理（急冷或缓冷）可以在表面形成不同的纳米结构，而在缓冷过程中，我们发现在多层石墨平台上生长出了纳米点、纳米线、纳米带、纳米缝隙、莫尔条纹和超结构等低维碳纳米结构。这些观察结果为阐明生长机制提供了很好的建议。在HOPG的新切割表面上也发现了类似的碳纳米线（JJAP，2007）。应当理解，轧制的石墨烯片或碳纳米线的成核和生长可能发生在由应力和应变产生的表面缺陷处，例如台阶边缘和原子空位。在快速冷却过程中，观察到纳米碳和单层石墨的初始形核。至于应用，我们已经证明了可重复使用的高分辨率STM针尖和AFM针尖形状表征的参考材料的用途。在C掺杂的Pt样品中，我们成功地合成了大面积的单层石墨烯薄膜。少

Synthesis of low-dimensional nano-carbons by using surface precipitation of dissolved carbon dopants is a novel fabrication method for nano-carbons without an external carbon source (Fujita et al, 2003, JJAP). It is required for us to control the variation of nano-carbons, based on the growth mechanism. The objective of the research is to clarify the growth mechanism on carbon-doped metal substrates by using surface nanocharacterization techniques, establish the method for synthesis and control of nano-carbons, and to explore the novel functionalities and applications. As for the specimens, various carbon-doped metals (mono-crystalline C-Ni (111), poly-crystalline C-Ni, C-Pt, C-Co, etc.) were prepared Carbon doping up to about 0.3 at% was performed by solid-state diffusion in vacuum at the elevated temperature. After polished and cleaned, the samples were heat-treated in UHV to fabricate nano-carbon films on the substrates, which were characterized by scanning probe microscopy (SPM) an … More d scanning Auger microscopy (SAM). In the case of C-Ni (111), it was found that different nanostructures appeared on the surfaces depending on the heat treatments (rapid cooling or gradual cooling).As for the gradual cooling, we discovered low-dimensional carbon nanostructures such as nanodots, nanowires, nanobelts, nano-crevices, Moire patterns, and superstructures, which were grown on multi-layer graphite terraces. The observations gave us good suggestions to clarify the growth mechanism. The similar carbon nanowires were also discovered on the freshly cleaved surfaces of HOPG (JJAP, 2007). It is understood that nucleation and growth of rolled graphen sheets, or carbon nanowires, may occur at surface defects such as step edges and atomic vacancies, generated by the stress and strain. In the caw of rapid cooling, initial nucleation of nano-carbons and monolayer graphite were observed. As for applications, we have demonstrated the uses for re-usable high-resolution STM tips and for reference materials for AFM tip-shape characterization. We have obtained the similar results for C-doped Co. In the case of a C-doped Pt sample, we have succeeded in the synthesis of monolayer graphene film with large area. Less