Ultrastable emission from a metal-oxide-semiconductor field-effect transistor-structured Si emitter tip

A silicon field emitter tip with a dual-gate metal-oxide-semiconductor field-effect transistor (MOSFET) structure was fabricated and demonstrated. The present tip structure is just the same as an n-channel MOSFET whose drain was replaced by a cone-shaped Si tip. Two coplanar gates of 0.3-mu m-thick Nb are made on a 0.6-mu m-thick thermally oxidized SiO2 insulator between the source and the tip and make inversion layers in ap-type Si substrate under each gate. One of the gates has a 1.8-mu m-diam aperture surrounding the tip for extraction of electrons from the tip. The other is 3 mu m wide and 300 mu m long and is separated by 2 mu m from this gate. Ultrastable emission of about 0.3 mu A was demonstrated with a single tip for one day. (C) 1996 American Institute of Physics.