Effect of morphology on electron emission characteristics of pulsed laser deposited diamond-like films

Electron field emission of diamond-like carbon (DLC) films synthesized by pulsed laser deposition technique at 400°C substrate temperature (0.1 mbar N2 ambient pressure) was turned on at a low electric field as E1 = 11.6 V/μm and a secondary deflection in current-voltage (I-V) curve occurred at E2 = 17.4 V/μm. The films attained a high emission current density as J = 120 μA/cm2 under 22 V/μm applied field. The effective work function estimated from the Fowler-Nordheim plot were φ′1 = 0.021 eV and φ′2 = 0.042 eV for low-turn-on regime (E1 < E2) and high-turn-on regime (E2 < E), respectively. The phenomenon of double φ′ with a low value in I-V characteristics was attributed to the presence of dual-morphology, i.e., the clusters and the wavy surface, which enhanced the electric field concentration with geometric factors of α1 = 72 and α2 = 36, respectively.