title: Synthesis of vertically aligned carbon nanofibers-carbon nanowalls by plasma-enhanced chemical vapor deposition.
abstract: Vertically aligned carbon nanofibers (VA-CNFs)-carbon nanowalls (CNWs) have been prepared on a silicon (Si) substrate by plasma-enhanced chemical vapor deposition. The VA-CNFs-CNWs were formed at bias voltage of - 185 V, whereas conventional VA-CNFs were synthesized under conditions of high bias voltages. Degenerated CNWs with turbostratic graphite structure were created on amorphous carbon layer around CNFs like a flag attached to a pole, which is evidenced by scanning electron microscopy, transmission electron microscopy, electron diffraction, and micro-Raman spectroscopy. Electron field emission characteristics of VA-CNFs-CNWs with unique microstructure, fabricated on the Si substrate, were primarily investigated. As a result, the VA-CNFs-CNWs showed the turn-on and the threshold fields of 1.7 V x microm(-1) and 3.35 V x microm(-1) with current densities of 10 nA x cm(-2) and 1 microA x cm(-2), respectively. The field enhancement factor beta was estimated to be 1059 by using Fowler-Nordheim theory.
authors.affiliation: Microstructure Control of Materials Laboratory, Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Atsuto
authors.initials: A
authors.lastname: Okamoto
authors.forename: Kei
authors.initials: K
authors.lastname: Tanaka
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yoshimura
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Ueda
authors.forename: Pradip
authors.initials: P
authors.lastname: Ghosh
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanemura