▎ 摘　　要

Improvements in field emission (FE) of graphene sheets were demonstrated by radio frequency magnetron sputtering with magnesium oxide (MgO). Following MgO coating, the turn-on field of graphene sheets is decreased from 6.3 to 3.8 V/mu m, and the threshold field is decreased from 9 to 6.5 V/mu m. The deposited MgO nanoparticles not only decrease the turn-on field but also enhance the tolerance ability of graphene sheets to various pressure conditions. Field emission stability measurements indicated better lifetime and field emission stability for MgO-coated graphene emitter. Meanwhile, atomic force microscopy, scanning electron microscopy, transmission electron microscope, and x-ray photoelectron spectroscopy were used to analyze the influence of MgO. This study presents an effective method of depositing wide-bandgap oxides on graphene emitters to improve the FE properties of graphene. (C) 2014 American Vacuum Society.