Abstract
The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 °C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2–30 walls with an inner diameter of 3–8 nm. Raman spectrum analysis shows G-band at 1580 cm−1 and D-band at 1340 cm−1. The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm2 at 1.2V/μm), low turn-on field (0.6 V/μm) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources.
Highlights
INTRODUCTIONPillar-shaped vertically aligned carbon nanotubes (CNTs) architectures have been synthesized by using a single-step water-assisted chemical vapor deposition (CVD) process that shows promising field-emission characteristics
We investigated the electron emission characteristics from pillar-shaped vertically aligned carbon nanotubes (CNTs) architectures using a parallel plate configuration for macroscopic emission characteristics and a 1 mm tungsten anode for microscopic emission measurements from individual nanotube
A parallel-plate configuration was used for field-emission measurements of as-grown samples in a high vacuum chamber, with a sample acting as the cathode and a phosphor-coated indium tin oxide (ITO) glass electrode acting as the anode for the visualization of field emission sites distribution
Summary
Pillar-shaped vertically aligned CNT architectures have been synthesized by using a single-step water-assisted CVD process that shows promising field-emission characteristics. This synthesis process usually involves different catalysts, barrier layers, carbon sources, and operation parameters, resulting in products with different morphologies and qualities. In water-assisted CVD synthesis process, the substrate SiO2/Si wafer supports the growth of CNTs where aluminium (Al) as a barrier layer and iron (Fe) as a catalyst for growth of CNTs. We investigated the electron emission characteristics from pillar-shaped vertically aligned CNTs architectures using a parallel plate configuration for macroscopic emission characteristics and a 1 mm tungsten anode for microscopic emission measurements from individual nanotube. The structure of as-synthesized vertically aligned CNTs-based pillar architectures are evaluated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy
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