A field emission device which shows very low turn-on voltage with large electrode spacing has been fabricated by applying KOH orientation-dependent etching to single crystal silicon. Aqueous KOH solutions create sharp angular structures bounded by (111) planes at an angle 54.74° from the (100) surface. Using this technique, “self-sharpening” tips were formed on silicon-on-insulator wafers. This process can be used to form lateral sharp edges that can act as both the cathode and the anode in a field emission device. The shapes of the tips were determined using transmission electron microscopy and the smallest emitter tip radius in this study was estimated to be 3 nm. These sharp emitters enable significant electron emission at low turn-on voltage even for large spacing between the emitter and the collector. The lowest turn-on voltage was found to be 27 V with emission currents of 10 μA at 1 μm spacing. Electron emission was observed even at an electrode spacing larger than 2 μm. The field enhancement factor (β) and field emission area (α) have been calculated using the Fowler-Nordheim equation. As expected, the field enhancement factor decreases with increasing electrode spacing. Failure mechanisms for the devices associated with high electric field are also discussed in this article. © 1999 American Vacuum Society.