Single-Step High-Yield Growth of Well Oriented Carbon Nanotubes by Plasma Enhanced Chemical Vapor Deposition*

The excellent electrical and mechanical properties of carbon nanotubes (CNTs) have enabled their incorporation in many commercial applications. In order to optimize the performance of CNT-based integrated electronics, it is desirable to develop a growth method that can produce highly-oriented CNTs with large aspect ratios. Here we report a new single-step seeded growth method of well oriented CNTs with high yields (up to 3 mg on ~ 1 cm² area within 10 minutes) by plasma-enhanced chemical vapor deposition (PECVD) on a substrate consisting of a thin copper layer on top of SiO₂/Si. Interestingly, we found that by varying the thickness of the copper layer on the substrate while keeping the same PECVD growth parameters, the carbon nanostructures synthesized ranged from graphene nano-stripes (with the long dimension up to ~ 10 μm on the substrate) to densely packed and vertically oriented CNTs (with the long dimension up to ~ 20 μm perpendicular to the substrate). Systematic studies of the growth parameters and the resulting structural and spectroscopic characteristics of these CNTs (determined by measurements of the Raman spectroscopy, XPS, UPS, SEM, AFM, TEM and EDS) are being carried out to optimize the growth conditions and to help unveil the growth mechanism.