Development of a multiscale model for the field electron emission properties of carbon-nanotube-based carbon fibers

A multiscale array model has recently been presented to describe field electron emission (FE) from carbon nanotubes (CNTs) on the apex of a carbon nanofiber (CNF) fabricated as a CNT aggregate. The model considered Joule heating, radiative cooling and Henderson/Nottingham cooling/heating, assumed CNT destruction at a specified tip temperature, and predicted the CNT fraction destroyed as a function of macroscopic field, and related current-voltage characteristics. The model reproduces features observed in recent experiments on FE from CNFs, including the emission current order-of-magnitude (mA range), the low turn-on field (fraction of V/μm), deviation at high field from the pure Fowler-Nordheim behavior expected for an undamaged CNT array, loops in current-voltage characteristics, and spatial variation of temperature along the CNF. Here, this array model is used to explore how some details of the CNT arrangement at the fiber apex (especially statistical variations in CNT geometry) might affect overall emission characteristics.