Field emission from flipped and patterned vertically aligned carbon nanotube arrays

Carbon nanotubes (CNTs) possess many unique properties that make them ideal for field emission. However, screening due to high density and poor substrate adhesion limits their application. We tested the field emission of various patterned vertically aligned carbon nanotube (VACNT) arrays adhered to copper substrates using carbon paste. After many fabrication steps to improve uniformity, we found that the field emission was dominated by individual CNTs that were taller than the bulk VACNT arrays. After testing a sample with silver epoxy as the binder, we found that the failure mechanism was adhesion to the substrate. Using energy dispersive x-ray spectroscopy, we found that the carbon paste migrated into the VACNT bulk volume while the silver epoxy did not. The migration of carbon paste into the volume may explain why the carbon paste had greater adhesion than the silver epoxy.