Electron field emission in air at an atmospheric pressure from sp ³-bonded 5H-BN microcones

Electron field emission (eFE) from s p3 -bonded 5H-BN films proved to take place in air at an atmospheric pressure. The eFE started at relatively low electric field (E) of 7.5 Vμm 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 B2 H6 +N H3 +Ar plasma where 193 nm 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 1 Vμm. 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 (4.3 eV, estimated by molecular orbital method). This atmospheric eFE combined with the robustness of BN may open a wide range of applications.