Scanning field emission from patterned carbon nanotube films

The investigation of the field emission (FE) properties of carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals a strong dependence on the density and morphology of the CNT deposit. Large differences between the microscopic and macroscopic current and emission site densities are observed, and explained in terms of a variation of the field enhancement factor beta. As a consequence, the emitted current density can be optimized by tuning the density of CNTs. Films with medium densities (on the order of 10(7) emitters/cm(2), according to electrostatic calculations) show the highest emitted current densities. (C) 2000 American Institute of Physics. [S0003-6951(00)00815-9].