Comment on slope of nonlinear FN plot and field enhancement factor

TL;DR

This paper clarifies misconceptions about how the slope of nonlinear Fowler-Nordheim plots relates to the field enhancement factor, emphasizing that the common interpretation of increasing enhancement with field is incorrect.

Contribution

The paper corrects the interpretation of nonlinear FN plot slopes, showing that the perceived increase in field enhancement factor with applied field is a misconception.

Findings

Multi-segment FN plots do not indicate increasing field enhancement factors.

Downward bending FN plots do not imply increasing enhancement factors.

The common interpretation of FN plot slopes is fundamentally flawed.

Abstract

It is common practice to extract field enhancement factor from the slope of FN plot. Many experimentalists working on field electron emission had reported multi-(linear segment) FN plots, which can be divided into several (usually two) linear segments. Then multi-(field enhancement factor) were extracted from the FN plot. They claimed that the field enhancement factor increases with applied field if the FN plot bends downward (vice versus if the FN plot bends upward). We show that this is contrary to fact.