Catalyst design for high-density and low-temperature CNT synthesis on conductive Ti silicide substrate

摘要

A multilayer (Ni/Al/Ni) catalyst design is proposed to synthesize high-density carbon nanotubes (CNTs) on a conductive titanium silicide substrate. The Al intermediate layer immobilizes the Ni catalyst on the substrate during nanoparticle formation by interacting with the top and bottom Ni catalyst film, suppressing the diffusion of Ni into silicide and sintering of the Ni nanoparticles, as evidenced by secondary ion mass spectroscopy and atomic force microscopy analysis. Owing to the stable, high-density and evenly distributed nanoparticle catalysts with the multilayer catalyst design, we have synthesized vertically aligned CNTs with a density of 2.0 x 10(10)/cm(2) and an average 50 walls per CNT. The CNT density using the Ni/Al/Ni catalyst is three times higher than that with the pure Ni catalyst. Furthermore, the proposed catalyst design enables CNT synthesis at a temperatures as low as 350 degrees C. The synthesized CNTs show Ohmic contact with Ti silicide, suggesting the catalyst design is promising for CNT applications on conductive substrates, especially for interconnect applications. (C) 2017 Elsevier B.V. All rights reserved.