High Performance Field Emitters

Cold cathode field emission from nanomaterials is an on‐going area of great academic and technological interest. There have been many suggested applications of field electron emission, including displays,1, 2, 3 traveling wave tubes,4, 5 microwave amplifiers,6, 7 electron microscopy,8, 9 parallel electron beam lithography,2, 10, 11 and X‐ray sources.2, 12, 13 Low work functions have been repeatedly touted as one of the primary drivers towards achieving high performance field electron emission.14, 15 However, detailed analysis of the way in which the work function affects the field emission has not yet been fully understood or comprehensively studied across a diverse range of materials. In the case of conventional bulk metallic systems, low work functions result in higher current densities relative to those materials with high work functions, as suggested by the established Fowler–Nordheim theory. As a result of this widely, and perhaps often incorrectly adopted theory, many have strived to develop low work function materials, composites, or coatings for enhanced field emitters.16, 17, 18 Empirical confirmation of the relative merits of low work function is, however, lacking. In this work, the effect of the work function and emitter dimensionality are studied in the largest meta‐analysis of its type.