Applying the Field Emission Orthodoxy Test to Murphy-Good Plots

Abstract

Abstract: In field electron emission (FE) studies, it is important to check and analyze the quality and validity of results experimentally obtained from samples, using suitably plotted current-voltage [Im(Vm)] measurements. For the traditional plotting method, the Fowler-Nordheim (FN) plot, there exists a so-called "orthodoxy test" that can be applied to the FN plot, in order to check whether or not the FE device/system generating the results is "ideal". If it is not ideal, then emitter characterization parameters deduced from the FN plot are likely to be spurious. A new form of FE Im(Vm) data plot, the so-called "Murphy-Good (MG) plot", has recently been introduced (R.G. Forbes, Roy. Soc. Open Sci. 6 (2019) 190912). This aims to improve the precision with which characterization-parameter values (particularly values of formal emission area) can be extracted from FE Im(Vm) data. The present paper compares this new plotting form with the older FN and Millikan-Lauritsen (ML) forms and makes an independent assessment of the consistency with which slope (and hence scaled-field) estimates can be extracted from an MG plot. It is shown that, by using a revised formula for the extraction of scaled-field values, the existing orthodoxy test can be applied to Murphy-Good plots. The development is reported of a prototype web tool that can apply the orthodoxy test to all three forms of FE data plot (ML, MG and FN). Keywords: Field emission, Field electron emission, Murphy-Good plot, Fowler-Nordheim plot, Millikan-Lauritsen plot, Orthodoxy test.