Controlling the density of CNTs by different underlayer materials in PECVD growth

In this paper, we present a new approach of controlling the growth density of carbon nanotubes (CNTs) by controlling the thickness of Cu underlayer. Tested thicknesses of Cu range from 5nm to 150nm. In this work, we have tried two kinds of barrier layer material, namely Mo and Al
₂
O
₃
against the diffusion of Ni catalysts. The results suggest Al
₂
O
₃
is a better barrier layer material and more suitable than Mo to be applied with Cu underlayer for the controlling of growth density of CNTs. In the end, this paper also gives a tentative explanation of this new method of controlling CNT growth density by adjusting the thickness of Cu underlayer.