Electron field emission in air at an atmospheric pressure from sp3-bonded 5H-BN microcones

Abstract

Electron field emission (eFE) from sp3-bonded 5H-BN films proved to take place in air at an atmospheric pressure. The eFE started at relatively low electric field (E) of 7.5V∕μm and was reproducible. The eFE in air obeyed the Fowler-Nordheim equation for quantum mechanical tunneling. The BN films with self-organized microcone emitters were prepared by chemical vapor deposition from B2H6+NH3+Ar plasma where 193nm excimer laser irradiated the growing film surface. The laser activates the growth reactions photochemically and induces the cone-shape formation. The eFE from the same sample observed in vacuum showed the threshold E below 1V∕μm. These excellent eFE properties are considered to originate from geometrical field enhancement by the microcone shape and the decrease of work function due to the surface electric dipole moment layer (4.3eV, estimated by molecular orbital method). This atmospheric eFE combined with the robustness of BN may open a wide range of applications.