【作者】 姜开利；

【Author】 Kaili Jiang;Department of Physics,Tsinghua University;

【机构】 清华大学物理系；

【摘要】 手性可控合成是目前单壁碳纳米管研究领域的热点问题。然而尚缺乏一种快速表征碳纳米管手性的方法。这里介绍一种低压扫描电子显微镜的方法,可以快速识别单壁碳纳米管的手征属性。例如金属性和半导体性碳纳米管在低压扫描电镜下表现出不同的衬度,亮的为金属性碳管,暗的是半导体性碳管。我们进一步发现,在金属-半导体接触处形成的肖特基结在低压扫描电镜下表现为一段微米长度的亮的衬度像,究其原因是由于耗尽层中的空间电荷所造成的。其长度正比于碳纳米管的直径,而半导体性碳纳米管的带隙反比于其直径,这样就可以利用它来快速评估单壁碳纳米管的带隙分布。这种低压扫描电镜表征手征属性的方法还可以用于其它纳米材料,为普通的扫描电镜增加了一些新的功能。更多还原

【Abstract】 Chirality controlled growth is a key challenge now in the research field of single-walled carbon nanotube(SWCNT). However, there is still no efficient method for evaluating the chiral indice distribution of as-grown SWCNTs. Here we show that low voltage SEM(LV-SEM) provides a high throughput way for probing the chirality-related information of SWCNTs. For example, metallic and semiconducting SWCNTs display different contrast in LV-SEM. The metallic one shows bright contrast while the semiconducting one shows dark contrast when connected to electrodes. Furthermore, the Schottky barrier at the metal-SWCNT contact can be clearly observed in LV-SEM as a bright contrast segment with length up to micrometers due to the space charge distribution in the depletion region. The lengths of the charge depletion increase with the diameters of semiconducting SWCNTs(s-SWCNTs) when connected to one metal electrode, which enables direct and efficient evaluation of the bandgap distributions of s-SWCNTs. Moreover, this approach can also be applied for a wide variety of semiconducting nanomaterials, adding a new function to conventional SEM.更多还原