Low-field electron emission from carbon cluster films: combined thermoelectric/hot-electron model of the phenomenon

Abstract

Thin carbon films consisting of separate nanometer-scale sp² carbon islands with smooth vacuum boundary deposited on Si wafers were found to be capable of low-field electron emission – starting from macroscopic field magnitudes as low as ～1?V/µm. For such films, we suggest a novel model of emission facilitation by thermoelectric field associated with heat generation concentrated in nanosized areas. Quantitative estimates performed on the basis of this hypothesis for typical experimental conditions gave estimates for local thermoelectric field magnitude and lateral non-uniformity of surface potential as high as ～100?V/μm and a few Volts, respectively. Thus, the suggested model explains the low-field emission capability of smooth-surface nanocarbon films observed in many previous experiments.