Characterization and field emission of sulfur-doped boron nitride synthesized by plasma-assisted chemical vapor deposition

Polycrystalline boron nitride (BN) films are synthesized using BCl3 and N-2 as source gases, by plasma-assisted chemical vapor deposition. BN films consist of nanocrystalline grains of 3 nm in size. The energy gap is estimated to be 6.0 eV from ultraviolet-visible optical transmission measurement. The electrical resistivity is also estimated to be 2 x 10(11) and 4.9 x 10(2) Ohm.cm for undoped and sulfur (S)-doped BN films, respectively. Electron field emission is observed from S-doped BN film deposited on the Si substrate. The emission current is detected at electric fields higher than 9 V/mu m. The emission current of 10 mu A is obtained at 21 V/mu m. This field emission characteristic is compared with that of polycrystalline diamond films treated with H-2 plasma.