A modified cathodic are technique has been used to deposit carbon nitride thin films directly on n(+) Si substrates. Transmission electron microscopy showed that clusters of fullerene-like nanoparticles are embedded in the deposited material. Field emission in vacuum from as-grown films starts at an electric field strength of 3.8 V/mum. When the films were etched in an HF:NH4F solution for 10 min, the threshold field decreased to 2.6 V/mum. The role of the carbon nanoparticles in the field emission process and the influence of the chemical etching treatment are discussed.