Field emission properties of amorphous carbon nitride thin films prepared by arc ion plating

Amorphous carbon nitride thin films (a-C:N) were deposited by means of shielded arc ion plating (SAIP) using nitrogen and graphite as an operating gas and a carbon source, respectively. In the applied field strength range of up to 20 V/μm, electron field emission properties of these films were characterized and compared with those of amorphous carbon (a-C) thin films prepared using an argon plasma by the same SAIP apparatus. The a-C:N films showed better characteristics, that is, lower threshold field strengths and higher maximum emission current densities, than the a-C films. Among all of the fabricated a-C:N films, the film with a N concentration of 23%, prepared using a nitrogen arc plasma at a pressure of 1 Pa with applying a sample bias voltage of −100 V, showed the lowest threshold field of approximately 13 V/μm and the highest emission current density of near 2 μA/cm2 at a field strength of 20 V/μm. However, the best results obtained on the a-C films were a threshold field of approximately 16 V/μm and an emission current density of less than 0.1 μA/cm2 at the same field strength. The characteristics of the a-C:N films depended not only on the N concentration but also on the chemical bonding state of nitrogen in the a-C:N networks. The C-N phase distinguished by the N1s XPS peak at 400.5 eV plays a crucial role in field emission of the a-C:N.