中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 21 Special 1 March 2011 |
vertically aligned carbon nanotubes/nanofibers
（1. Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave,
Cambridge MA 02139, USA;
2. National Core Research Center for Hybrid Materials Solution, Pusan National University,
Busan 609-735, Korea）
Abstract:The etching effect of ammonia (NH3) on the growth of vertically aligned nanotubes/nanofibers (CNTs) was investigated by direct-current plasma enhanced chemical vapor deposition (DC-PECVD). NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time (5 min) than large catalytic patterns (10 min) since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy (HTEM) shows fishbone structure of CNTs grown by PECVD.
Key words: carbon nanotube; ammonia etching; nickel catalyst; plasma enhanced chemical vapor deposition (PECVD)
