Amorphous carbon-nitride films were grown on the nitridated-diamond substrates by pulsed-discharge of pure nitrogen gas using graphite rods as the discharge electrodes. The deposition conditions were optimized by monitoring the discharge plasma with optical-emission spectroscopy. It is demonstrated that the films were mainly a mixture of nanosized carbon and carbon-nitride with sp2 and sp3 phases. Preliminary results show that the deposited carbon-nitride films exhibit semiconductor behavior and have a cold-cathode-emission property, which make them possible to be superior electronic materials. Improvement in the conductivity and field-emission properties was observed after chemical etching with hydrofluoric acid. The activation energy for electrical conduction of the HF-treated film decreased from 3.42 to 1.19 eV. The similar threshold voltages were obtained for the carbon-nitride films before and after chemical etching, which were 4.0 and 3.5 V/μm, respectively. However, the emission current density after etching increased by one order of magnitude.