Deposition and field-emission characterization of electrically conductive nitrogen-doped diamond-like amorphous carbon films

For the fabrication of high performance field emitters, diamond-like amorphous carbon films doped with nitrogen (DAC:N) were formed using an intermittent supermagnetron plasma chemical vapor deposition technique. DAC:N films were deposited using isobutane plasma to investigate the influence of discharge-off time and electrode spacing on the physical properties of the films at upper- and lower-electrode radio frequency (rf) powers (LORF) of 800 W/50-800 W. At LORF of 100 W, a discharge-on time of 1 min, and a discharge-off time (cooling time) of 30 s-10 min, resistivity was decreased with a decrease of the cooling time. By reducing the electrode spacing from 60 to 20 mm at a LORF of 50 and 800 W, the optical band gap of DAC:N film was decreased from 0.85 and 0.23 eV to 0.6 and 0 eV, respectively. A flat DAC:N film of 700 A thickness was deposited on a n-Si wafer at rf powers of 800 W/800 W. Using this flat DAC:N film, a threshold electric field of 18 V/μm was observed and maximum field-emission current density of 2.2 mA/cm2 was observed at the electric field of 32 V/μm