Novel lateral field emission device fabricated on silicon-on-insulator material

A field emission device which shows very low turn-on voltage with large ele ctrode spacing has been fabricated by applying KOH orientation-dependent et ching to single crystal silicon. Aqueous KOH solutions create sharp angular structures bounded by (111) planes at an angle 54.74 degrees from the (100 ) surface. Using this technique, "self-sharpening" tips were formed on sili con-on-insulator wafers. This process can be used to form lateral sharp edg es that can act as both the cathode and the anode in a field emission devic e. The shapes of the tips were determined using transmission electron micro scopy and the smallest emitter tip radius in this study was estimated to be 3 nm. These sharp emitters enable significant electron emission at low tur n-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 1 0 mu A at 1 mu m spacing. Electron emission was observed even at an electro de spacing larger than 2 mu m. The field enhancement factor (beta) and fiel d emission area (alpha) have been calculated using the Fowler-Nordheim equa tion. As expected, the field enhancement factor decreases with increasing e lectrode spacing. Failure mechanisms for the devices associated with high e lectric field are also discussed in this article. (C) 1999 American Vacuum Society. [S0734-211X(99)00904-X].