Evidence for Adsorbate-Enhanced Field Emission from Carbon Nanotube Fibers

TL;DR

This study demonstrates that hydrogen adsorbates significantly enhance field emission from carbon nanotube fibers, with desorption correlating to emission thresholds and a model explaining the transition from adsorbate-enhanced to intrinsic emission.

Contribution

It provides the first direct evidence linking H2 desorption to FE threshold and introduces a comprehensive model for the adsorbate-driven emission transition.

Findings

H2 desorption occurs at a specific threshold field coinciding with FE breakpoints

A model explains the transition from adsorbate-enhanced to intrinsic FE

Self-heating and alignment effects influence FE behavior

Abstract

We used residual gas analysis (RGA) to identify the species desorbed during field emission (FE) from a carbon nanotube (CNT) fiber. The RGA data show a sharp threshold for H2 desorption at an external field strength that coincides with a breakpoint in the FE data. A comprehensive model for the gradual transition of FE from adsorbate-enhanced CNTs at low bias to FE from CNTs with reduced H2 adsorbate coverage at high bias is developed which accounts for the gradual desorption of the H2 adsorbates, alignment of the CNTs at the fiber tip, and importance of self-heating effects with applied bias.