Department of Chemistry, Duke University , Durham, North Carolina 27708, United States.
ACS Nano. 2014 Jan 28;8(1):554-62. doi: 10.1021/nn405105y. Epub 2013 Dec 6.
Single-walled carbon nanotubes (SWNTs) are highly desired for future electronic applications due to the excellent electrical, mechanical, and thermal properties. However, the density and the selectivity in the growth of aligned semiconducting nanotubes do not coexist previously: when the selectivity is high, the density is low and vice versa. In the present work, we found that random carbon nanotubes (CNTs) in the catalyst area block the growth of aligned SWNTs along the lattice structure on the quartz surface, thus significantly reducing the density of nanotubes during growth. More interestingly, it was shown that the random CNTs can be selectively removed through appropriate treatments using water vapor as an in situ etchant while the aligned SWNTs survive even after long-time water vapor treatment. To obtain high-density semiconducting SWNT arrays, we designed an improved multiple-cycle growth method, which included the treatment of SWNTs with water vapor after each growth cycle without cooling the system. Using this method, we have successfully obtained dense semiconducting SWNTs (∼10 SWNTs/μm) over large areas and with high uniformity.
单壁碳纳米管 (SWNTs) 由于其优异的电学、力学和热学性能，在未来的电子应用中备受期待。然而，以前定向生长半导体纳米管的密度和选择性不能共存：选择性高时，密度低，反之亦然。在本工作中，我们发现催化剂区域内的随机碳纳米管 (CNTs) 会阻碍沿石英表面晶格结构生长的定向 SWNTs，从而在生长过程中显著降低纳米管的密度。更有趣的是，我们发现通过使用水蒸气作为原位蚀刻剂进行适当的处理，可以选择性地去除随机 CNTs，而即使经过长时间的水蒸气处理，定向 SWNTs 也能存活下来。为了获得高密度半导体 SWNT 阵列，我们设计了一种改进的多循环生长方法，该方法包括在每个生长循环后用水蒸气处理 SWNTs，而无需冷却系统。使用这种方法，我们已经成功地在大面积上获得了高密度的半导体 SWNTs（约 10 根 SWNTs/μm），且具有很高的均匀性。
