Electron field emission from boron-nitride nanofilms

Hexagonal polycrystalline boron-nitride (BN) films are synthesized on Si substrates by plasma-assisted chemical-vapor deposition. In the case of BN films thicker than 20 nm, the turn-on electric field of the electron emission decreases with increasing surface roughness. On the other hand, in the case of BN film as thin as 8–10 nm, it is found that the turn-on electric field is reduced to 8.3 V/μm in spite of the surface of the BN nanofilm being flat, as well as the Si substrate. The Fowler–Nordheim (FN) plot of the field-emission characteristics of the BN nanofilm indicates a straight line, suggesting the presence of FN tunneling. This finding means that introduction of the BN nanofilm leads to a significant reduction in the effective potential barrier height.