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 10 12 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.