Surface electronic structure analysis of high current electron source materials and extreme operation analysis of FEAs

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Electron emission from a field emitter array (FEA), especially Spindt type FEA was magnified by making use of an emission microscope, and uniformity and stability of the emission current were examined. Percentage of the active microtips was usually 40-50%, maximum value was 90%.The stability of the emission current was less than 10%, and the emission current fluctuation should be caused by the ion bombarding. The emission current and its uniformity was improved with the introduction of low pressure gas. Hydrogen and nitrogen gas showed the cleaning effect. Methane and ethylene gas showed the increasing of the emission current. The n-type Si FEA was also observed by emission microscope. The Si FEA showed large fluctuation than the Spindt type FEA. W (100) needle was covered with Yttrium oxide to improve the emission current density. Such YO/W (100) emitter showed low work function value (2.1eV). Mo (100) needle covered with Zirconium oxide also showed low work function (2.0eV).