Microscopic characterization of electron field emission

We report on the functional capabilities of a scanning anode field emission microscope (SAFEM) which combined with a phosphor screen is used to investigate and correlate individual electron emission site characteristics of low threshold thin film electron emitters in the micrometer regime. Spatially recorded extraction voltage $\mathrm{V(x,y)}$ maps under constant emission current or emission current $\mathrm{I(x,y)}$ maps under constant anode voltage reveal spatially divergent emission properties on thin film emitters. The $\mathrm{V(x,y)}$ maps are used to derive the field enhancement $\mathrm{\beta (x,y)}$ maps which give a better description of the thin film emission properties as compared to electric threshold fields which depends on anode-cathode geometry. Individual emission site current stability of thin film emitters can be investigated with the SAFEM, and a high-resolution field emission microscope to investigate the environmental stability of single carbon nanotubes mounted on filaments as a function of partial gas pressures and temperature.