Middle-ultraviolet laser photoelectron emission from vertically aligned millimeter-long multiwalled carbon nanotubes

We demonstrate photoelectron emission from millimeter-long forests of vertically aligned multiwalled carbon nanotubes using 266 nm light, which illuminates the forests from the side. We have measured quantum efficiencies in the order of ∼10−5 at low fields (pure photoemission) and ∼10−3 at an applied field of 0.3 V μm−1, which are 2–4 orders of magnitude higher than those obtained from films of randomly oriented nanotubes, and approach the quantum efficiency of semimetal photocathodes. Through optical simulations we show that 266 nm light is absorbed within the first few layers of the nanotube forest.