Carbon Nanotube Field Emitters Synthesized on Metal Alloy Substrate by PECVD for Customized Compact Field Emission Devices to Be Used in X-Ray Source Applications

Abstract

In this study, a simple, efficient, and economical process is reported for the direct synthesis of carbon nanotube (CNT) field emitters on metal alloy. Given that CNT field emitters can be customized with ease for compact and cold field emission devices, they are promising replacements for thermionic emitters in widely accessible X-ray source electron guns. High performance CNT emitter samples were prepared in optimized plasma conditions through the plasma-enhanced chemical vapor deposition (PECVD) process and subsequently characterized by using a scanning electron microscope, tunneling electron microscope, and Raman spectroscopy. For the cathode current, field emission (FE) characteristics with respective turn on (1 μA/cm2) and threshold (1 mA/cm2) field of 2.84 and 4.05 V/μm were obtained. For a field of 5.24 V/μm, maximum current density of 7 mA/cm2 was achieved and a field enhancement factor β of 2838 was calculated. In addition, the CNT emitters sustained a current density of 6.7 mA/cm2 for 420 min under a field of 5.2 V/μm, confirming good operational stability. Finally, an X-ray generated image of an integrated circuit was taken using the compact field emission device developed herein.

Modelling of Electric Field Strength Amplification at the Tips of Thin Conductive Rods Arrays

“…Development of technologies for carbon nanotubes (CNTs) production leads to their usage in different areas, such as creation of the cold field emission cathodes that operate at relatively low applied voltage levels [3][4][5]. This becomes possible due to the large ratio of the CNT height to their radius, as well as their high electric conductivity.…”

“…The cases when a ratio of the rods height (H) to their radius (R) can reach 10 2 -10 4 and more are considered. Another area of such problems' application is the emission devices using arrays of carbon nanotubes (CNTs) [3][4][5]. According to [6], the problem of determination of the EF strength amplification at the tips of the CNT array: β = E max /E 0 (where E max is maximum EF strength at the rods tips, and E 0 is the average applied EF strength), depending on their parameters, is not completely solved despite that it has been considered in many researches.…”

The Growth Methods and Field Emission Studies of Low-Dimensional Boron-Based Nanostructures

“…In recent studies, low-power nanostructure-based microwave electron tubes were observed to exhibit nice performances, in which 27.5 W output power and 19.5 dB gain have been achieved at a frequency of 10.5 GHz, a helix voltage of 3.35 kV and a cathode current of 58.6 mA [98,99]. In addition, carbon NTs [100][101][102][103][104] and ZnO NWs [105] were used as X-ray sources with a spatial resolution of less than 25 µm. In the meantime, a single LaB 6 NW with growing along <001> direction was fabricated into the electron gun of the SEM system by H. Zhang et al [97] because of its outstanding FE behaviors.…”

Adsorbate-enhanced field-emission from single-walled carbon nanotubes: a comparative first-principles study

“…, where E is the electron energy, H is the three-dimensional device Hamiltonian constructed in a real space basis, i is the unit imaginary number, 0  is an infinitesimally small positive number, and 1  , 2  are the self-energy terms that account for the coupling of the contacts to the channel. It is worth mentioning that, in the structures studied in this work, the hydrogen termination of the dangling bond at the CNT end creates an undesired local dipole because carbon is more electronegative than hydrogen.…”