We have fabricated nanocrystalline Si planar cathodes and investigated their emission characteristics. The device is composed of a thin metal film, nanocrystalline silicon (nc-Si) particles covered with an oxide film, an n-type silicon substrate, and a bottom electrode. The nc-Si layers were deposited by a pulsed laser ablation technique using a Si target and their surface was oxidized by an oxygen radical beam source generated by radio frequency discharge. The electron emission occurred at the gate voltage higher than the work function of the gate metal, and the emission efficiency was 0.5%. The energy distribution of emitted electrons was considerably broad, indicating that electrons were strongly scattered inside the nc-Si layer and the gate electrode. (c) 2006 American Vacuum Society.