▎ 摘　　要

Graphene was used as the topmost electrode for a metal-oxide-semiconductor planar-type electron emission device. With several various layers, graphene as a gate electrode on the thin oxide layer was directly deposited by gallium vapor-assisted chemical vapor deposition. The maximum efficiency of the electron emission, defined as the ratio of anode current to cathode current, showed no dependency on electrode thickness in the range from 1.8 nm to 7.0 nm, indicating that electron scattering on the inside of the graphene electrode is practically suppressed. In addition, a high emission current density of 1-100 mA/cm(2) was obtained while maintaining a relatively high electron emission efficiency of 0.1%-1.0%. The graphene-oxide-semiconductor planar-type electron emission device has great potential to achieve both high electron emission efficiency and high electron emission current density in practical applications. (C) 2016 AIP Publishing LLC.