Electron field emission from single-walled carbon nanotube nonwoven

Field emission from single-walled carbon nanotube (SWNT) nonwoven has been investigated under high vacuum with different vacuum gaps. A low turn-on electric field of 1.05\,V/$\mu $m is required to reach an emission current density of 10 $\mu $A/cm$^{2}$. An emission current density of 10 mA/cm$^{2}$ is obtained at an operating electric field of 1.88\,V/$\mu $m. No current saturation is found even at an emission current of 5\,mA. With the vacuum gap increasing from 1 to 10 mm, the turn-on field decreases monotonically from 1.21 to 0.68\,V/$\mu $m, while the field amplification is augmented. The good field-emission behaviour is ascribed to the combined effects of the intrinsic field emission of SWNT and the waved topography of the nonwoven.