Prebreakdown Currents From Tungsten Samples Covered With Thin Films

The results of current-voltage characteristics (CVCs) of low-field emission (LFE) measurement from tungsten cathodes covered by a thin (~10 Å) discontinuous insulator film are presented. Such characteristics have a strong hysteresis effect and can be interpreted by switch-ON model. The current density of LFE is significantly higher than that of pure tungsten and comparable with that of tungsten fuzz nanostructure-the surface with high emissivity. The influence of water adsorption layers on the emission currents demonstrates increasing hysteresis effect in the CVCs in the case of cathode exposition under the injection without voltage applying in vacuum diode.