Influence of the Plasma Condition on the Morphology of Vertically Aligned Carbon Nanotube Films Grown by RF Plasma Chemical Vapor Deposition

Abstract

Vertically aligned carbon nanotube (VACNT) films have been grown by RF plasma chemical vapor deposition (RF-PECVD) with a controlling plasma condition. From the in situ optical emission spectroscopy (OES) and self-bias measurements, we have investigated the relationship between the morphology of VACNTs and the plasma condition in PECVD. CH radical and atomic hydrogen peaks were prominent in the OES spectra of CH 4 plasma. The plasma condition was changed by varying the interelectrode distance in PECVD. With increasing interelectrode distance, the diameter and density of VACNTs increased as a result of the increase in plasma density, the fraction of CH radicals, and self-bias. It is likely that the fraction of CH radicals in plasma influences promotion of the growth of CNTs, while the self-bias induces their vertical alignment.

Direct Observation of Plasma-Stimulated Activation of Surface Species Using Multimodal In Situ/Operando Spectroscopy Combining Polarization-Modulation Infrared Reflection-Absorption Spectroscopy, Optical Emission Spectroscopy, and Mass Spectrometry

“…57 The observation that the optical emission spectra are similar for all surfaces indicates that the surface type did not strongly affect the plasma production of key CH 4 -derived radical species that lead to carbonaceous deposits. 58,59 Thus, the difference in the type of CH x species observed on each surface is likely due to the relative activity of Ni, SiO 2 , and KBr toward CH x formation.…”

Influence of plasma condition on carbon nanotube growth by rf-PECVD

“…Another common plasma reactor is microwave plasma CVD which uses a 2.45 GHz microwave generator to supply power for the plasma [8][9][10][11]. Radio frequency plasma CVD, divided into inductively coupled plasmas (ICPs) and capacitively coupled plasmas, also provides high-density plasma source with 13.56 MHz power supply for CNTs growth [3][4][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The types of plasma reactor greatly affected the plasma condition and thus the growth environment for CNTs.…”

“…Furthermore, the plasma condition could also be changed by varying the interelectrode distance in PECVD resulting in the variation of diameter and density of CNTs [27]. However, how the plasma condition exactly affects the growth of CNTs is not clear.…”