Electron field emission and surface morphology of a-C and a-C:H thin films

Hydrogen-free amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) films have been deposited on (100)-oriented single crystal Si substrates by cathodic-arc vacuum deposition (CAVD) with and without ion beam assistance and also plasma-enhanced chemical vapour deposition. The field emission characteristics of films were measured by a diode technique. Prior to emission characteristics measurements, the films were annealed under vacuum for 1 h at 350 and 950 °C. On the basis of Raman spectroscopy analyses, it was established that the field emission takes place for films with high content of sp2 carbon sites. The increase in sp2 carbon sites is the result of application of the ion beam assistance during deposition of films and effect of the annealing treatment at 950 °C. The a-C films formed by CAVD method with ion-beam assistance having developed surface morphology possesses improved emission characteristics. It was observed that in annealed a-C:H films, the activating emission centers are active as a direct electrical field of 12 V/μm is applied to their surface.