Abstract
Field electron emission (FE) sources are made close to atomic-scale to reach the highest spatial resolution and stable emission for electron microscopy, electron beam inspection, and lithography. At present, no single agreed method exists for using FE current–voltage data to extract the apparent emission area, which is needed for predicting some beam properties. The 1956 theory of Murphy and Good (MG) is better physics than the 1920s theory of Fowler and Nordheim (FN) and colleagues, but many researchers use simplified FN theory to analyze experimental data. The present paper reports an experimental method of finding the apparent emission area, based on using field ion and field electron microscopes (FIM+FEM). The emission area discrepancy between the FIM+FEM method and MG-based analysis is a factor of 8.2, but the discrepancy with simplified FN-based analysis is about 28, confirming that MG theory is better for FE data analysis. The result allows the deduction of key indicators, including source energy spread, reduced brightness, and emission efficiency. A downloadable program is made available to help with data analysis. Our work provides a new experimental method of characterizing FE sources, especially atomic-scale cold cathodes, for which existing plot-based data-analysis methods are not suitable.