Development of simple quantitative test for lack of field emission orthodoxy

TL;DR

This paper introduces a simple quantitative test to evaluate the validity of reported field enhancement factors in cold field electron emission data, helping identify spurious results and ensuring more accurate characterization of emitters.

Contribution

It defines an orthodoxy framework for CFE, derives a test for non-orthodox behavior from historical data, and demonstrates its application to recent nanostructure experiments.

Findings

Some FEF values are unreasonably high, indicating spurious results.

The test applies broadly to any diode geometry and FN/ML plots.

Mathematically proves that high f-values imply spuriously large FEFs.

Abstract

This paper describes a simple quantitative test applicable to current-voltage data for cold field electron emission (CFE). It can decide whether individual reported field-enhancement-factor (FEF) values are spuriously large. The paper defines an "orthodox emission situation" by a set of ideal experimental, physical and mathematical conditions, and shows how (in these conditions) operating values of scaled barrier field (f) can be extracted from Fowler-Nordheim (FN) and Millikan-Lauritsen (ML) plots. By analyzing historical CFE experiments, which are expected to nearly satisfy the orthodoxy conditions, "apparently reasonable" and "clearly unreasonable" experimental ranges for f are found. These provide a test for lack of orthodoxy. For illustration, this test is applied to 17 post-1975 CFE data sets, mainly for carbon and semiconductor nanostructures. Some extracted f-value ranges are apparently reasonable (including many carbon results), some are clearly unreasonable. It is shown that this test applies to any field-emission diode geometry and any form of FN or ML plot. It is proved mathematically that, if the extracted f-value range is "unreasonably high", then FEF-values extracted by the usual literature method are spuriously large. Probably, all new field-emitter materials should be tested in this way. Appropriate data-analysis theory needs developing for non-orthodox emitters.