Electron emission characteristics of sulfur (S)-doped boron nitride (BN) films synthesized by plasma-assisted chemical vapor deposition (PACVD) are investigated. The BN film consists of hexagonal grains of 3 nm in size. The energy gap is estimated to be as wide as 6.0 eV from ultraviolet-visible optical transmission measurement. The electrical resistivity is reduced to4.9×102 &OHgr; cm.Si tip field emitters coated with the BN film are fabricated. The electron emission occurs at an electric field as low as 6 V/&mgr;m, while a high electric field of 20 V/&mgr;m is needed to emit electrons from the Si tip array without BN coating. It is deduced that the tunneling barrier height of 0.1 eV exists at the surface of the BN film. ©1997 American Institute of Physics.