原位电子束诱导沉积制备碳纳米结构

Carbon nanostructures fabricated by in situ electron beam induced deposition

以多壁碳纳米管为基本材料,利用电子束诱导沉积的方法进行了纳米结构加工、修饰研究。电子束诱导沉积实现了二个碳纳米管端部之间的牢固焊接,实现了纳米材料间的几乎无损伤连接。原位测量表明多壁碳纳米管间的连接为欧姆接触。进一步对碳纳米管施加外电场可以使端部碳原子间的π键打开,外部碳原子经电子束诱导沉积在碳纳米管的端部,并定向生长成非晶态碳纳米线。由于碳纳米管和纳米线结合处的σ键作为绝缘界面,形成了电子输运的势垒,所得到的碳纳米管-纳米线复合结构具有整流特性。利用电子显微镜进行纳米材料的结构加工、修饰,具有选择位置精确、可实时监测、对纳米材料几乎无损伤、重复性和可靠性高,以及加工尺度可人为控制的特点。

Nanostructures of multi-walls carbon nanotubes were fabricated using in situ electron beam deposition. Under strong electrical field the tip structure of carbon nanotube became instable and existed in the electron microscope column hydrocarbon incorporated into the tip of carbon nanotube, as a result amorphous carbon nanowires initialized on the top of multi-walls carbon nanotube and fast grew up orientationally in the form of many branches, leading to the carbon nanotube-nanowire nanostructure with fractal feature. The tip to tip junction of carbon nanotubes was also fabricated by in situ electron beam deposition. The perfect wettability establishesd a strong mechanical binding between the two nanotubes to form an integrated structure. The joint dimension was determined by the spot size of electron beam, which resulted in a sound junction with the well-defined geometry and minimum junction size. In situ electric measurements indicated that the multi-walled nanotubes junction had a linear current-voltage property, whereas nanotube-nanowire structure behas the rectify characteristic.