The Influence of a TiN Buffer Layer on the PECVD Growth and Field Emission Properties of Carbon Nanotubes

Abstract

This study explores the growth and field emission properties of carbon nanotubes (CNTs) prepared using Fe catalyst layers on TiN coated Si substrates. TiN buffer layers were employed as a catalyst support in the plasma enhanced chemical vapor deposition (PECVD) growth of the CNT films. The TiN layers were characterized by x-ray photoelectron spectroscopy, atomic force microscopy, and photo electron emission spectroscopy to establish the interaction of the Fe catalyst film with the TiN buffer layer and underlying substrate. The TiN layers were shown to directly influence the growth process by enabling the catalyst to remain in an active state.

The PECVD grown CNT films exhibited field emission current densities of 1 mA⁄cm2 at applied fields of ˜2.1 V⁄μm. The emission distribution from the films, observed using a phosphor coated screen, was found to be uniform over selectively deposited areas up to 3.24 cm2. Non-linearity in the Fowler-Nordheim emission plots of the CNT films was shown to originate from adsorbate effects which have in many cases led to misleading analysis of field emission data. The uniform distribution of emission sites and the excellent field emission properties of the CNT films indicate that TiN, unlike SiO2, effectively functions as a catalyst barrier for growth without significantly impeding electron transport from the substrate to the emitter structures.