Electron field emissions from two well contrasted phase microstructures of magnetron-sputtered boron nitride (BN) films on Si (100) substrate, characterized by the Fourier transform infrared (FTIR) spectroscopy, were thoroughly investigated in this work. Compared with a mediocre turn-on field of about 18 V/mu m for the field emission from a pure hexagonal boron nitride (h-BN) film, a remarkably low turn-on field of about 5 V/mu m as well as excellent emission current density has been observed stably from a highly cubic boron nitride (c-BN) film. Aside from the geometric field enhancement, the excellent field emission properties of high cubic phase BN may originate from the assisting of c-BN phase with intrinsically negative electron affinity (NEA) and the special SP3 bonding of c-BN. (c) 2006 Elsevier B.V. All rights reserved.