Field emission enhancement of carbon nitride films by annealing with different durations

Magnetron sputtered carbon nitride films (CN x) were annealed at 750 deg. C for periods from 30 to 120 min. Effects of annealing with different durations on the field emission of CN x films were investigated and related to the variations of chemical bonding and surface morphology induced by annealing. The results show that annealing effectively enhances field emission ability of the CN x films and that the threshold field was lowered from 13 to 5 V/μm. The measurements of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) indicated that annealing leads to a loss of N content and to formation of more graphite-like sp2 C clusters in the films, and simultaneously the film surface becomes rougher after annealing, all of which is attributed to the increased film field emission. A large number of sp2 C clusters with good conductivity enables tunneling in the film, making electron emission easier, and moreover, a rougher surface also improves the field enhancement factor of the films. However, continuing to increase annealing time eventually lowers the field emission of the films