Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region

A stable field emission (FE) under a high residual pressure (10-5 Torr) was obtained by the thermal field operation of a nanoneedle cathode with a two dimensional graphene sheet structure. A high brightness electron emission of the order of 1012 A sr-1 m-2, as well as stable emission, was achieved. The performance of the stabilized cathode was demonstrated by the construction of a compact FE scanning electron microscope (SEM) system, and clear FE-SEM images were obtained at a residual pressure above 10-5 Torr. The emission current fluctuation as a function of cathode temperature was discussed based on the Poisson distribution.