High-performance planar-type electron source based on a graphene-oxide-semiconductor structure

A graphene-oxide-semiconductor (GOS) planar-type electron source was fabricated by direct synthesis of graphene on an oxide layer via low-pressure chemical vapor deposition. It achieved a maximum electron emission efficiency of 32.1% by suppressing the electron inelastic scattering within the topmost gate electrode using a graphene electrode. In addition, an electron emission current density of 100 mA/cm^2 was observed at an electron emission efficiency of 16.2%. The electron energy spread was well fitted to Maxwell-Boltzmann distribution, which indicates that the emitted electrons are the thermally equilibrium state within the electron source. The full-width at half-maximum energy spread of the emitted electrons was approximately 1.1 eV. The electron emission efficiency did not deteriorate after more than 42 h of direct current operation. Thus, the GOS planar-type electron source has the potential to be an excellent electron gun for electron microscopy.
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