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Development of a simple quantitative test for lack of field emission orthodoxy

The orthodox emission hypothesis is a set of physical and mathematical assumptions that permit well-specified analysis of measured current–voltage data relating to field electron emission (FE). If these assumptions are not adequately satisfied, then widely used FE data-analysis methods can generate spurious values for emitter characterization parameters, particularly field enhancement factors (FEFs). This paper describes development of a simple quantitative test for whether FE data are incompatible with the hypothesis. It applies to any geometrical emitter shape and any Fowler–Nordheim (FN) plot type, and involves extracting the related range of scaled-barrier-field values (f values). By analysing historical data, this paper identifies ‘apparently reasonable’ and ‘clearly unreasonable’ experimental ranges for f. The historical data, taken between 1926 and 1972, are internally self-consistent. This test is then applied to 19 post-1975 datasets, mainly for various carbon and semiconductor nanostructures. Some extracted f-value ranges (including many carbon results) are apparently reasonable, some are clearly unreasonable. It is shown that if extracted f values are ‘unreasonably high’, then FEF values extracted by literature methods are spuriously large. New materials and published FN plots that generate particularly high FEF values require testing, and improved data-analysis theory is needed for non-orthodox emitters. A spreadsheet for implementing the test is provided.