Vacuum Cold Cathode Emitter Electronic Devices Comprised of Diamond or other Carbons

Abstract

Field emitter arrays (FEAs) need improved novel cold cathode materials for better and more reliable performance. The presence of negative electron affinity (NEA) on hydrogen-terminated diamond surfaces, coupled with practical chemical vapor deposition (CVD) processing of deposited diamond as a thin film on a variety of substrates, has promoted further interest in the use of diamond and diamond-like carbon materials as field emitters. Experimentally, diamond and carbon nanotube emitters have been observed to emit electrons at relatively low electric fields and generate useful current densities. In this work, nanocarbon-derived vacuum devices, viz., the nanodiamond lateral diode and the gated carbon nanotube triode are examined. The material properties, device structure and fabrication process, and the electrical performance of the two configurations are presented. Nanocarbon-derived electron emission devices, specifically, nanodiamond lateral field emission diodes and gated lateral field emission diamond and carbon nanotube triodes are new configurations for robust nanoelectronic devices. These novel micro/nanostructures provide an alternative and efficient means of accomplishing electronics that are impervious to temperature and radiation. For example, nitrogen-incorporated nanocrystalline diamond has been lithographically micropatterned to utilize the material as an electron field emitter. Arrays of laterally arranged "finger-like" nanodiamond emitters constitute the cathode in a versatile diode configuration with small interelectrode separation. A low diode turn-on voltage of 7 V and a high emission current of 90 muA at an anode voltage of 70 V (electric field of ~ 7 V/mum) is reported for the nanodiamond lateral device. Also, a field emission triode amplifier based on aligned carbon nanotubes (CNTs) with low turn-on voltage and small gate leakage current has been developed.