Structural degradation mechanism of multiwalled carbon nanotubes in electrically treated field emission

Carbon nanotubes in printed field emission arrays are known to be often damaged during field emission. A high-resolution transmission electron microscopy and Raman scattering spectra suggest that the degraded structure is mainly determined by electrical treatment conditions. A nonstationary alternating-current treatment has caused emitters to be thicker and fewer with loss of crystallinity but improved the emission brightness and uniformity, while a direct-current treatment has shown little influence. The experimental observations can be quantitatively explained by the analytical estimation on the apex radius as well as the work function using the Seppen–Katamuki chart from the Fowler–Nordheim characteristics.