A planar cathode based on nanocrystalline Si covered with a thin oxide film was fabricated and the emission characteristics were examined. The electron emission occurred at the gate voltage higher than the work function of the Au gate, and the emission efficiency was improved up to 4% by reducing the thickness of the Au electrode. A lot of nanoholes in the thin Au film were observed, suggesting emission included electrons directly emitted from nanocrystalline aligned under nanoholes. The energy distribution of the emitted electron and the emission angle of the cathode are also discussed. (c) 2008 American Vacuum Society.