A Vacuum Insulator Negative Electron Affinity Electron Emitter with High Quantum Efficiency

Previous studies of planar graphene-oxide-semiconductor (GOS) structures have highlighted Fowler-Nordheim (FN) tunneling through the oxide layer as the dominant mechanism for electron emission[1]. Scattering within the oxide layer limits electron emission but can be counteracted by generating hot-electrons through optical excitation in the underlying semiconductor[2]. Still, the scattering in the oxide persists, limiting the current emission efficiency. Additionally, trapping of electrons causes broadening of the emitted electron energy spectrum. A novel graphene-vacuum-semiconductor (GVS) structure is developed. By eliminating the oxide layer, the tunneling mechanisms can be reduced to Fowler-Nordheim exclusively. As a result, emitted electrons will have an energy spread limited by that of the semiconductor and scattering in the graphene[2]. Additionally, electron trapping in the oxide is eliminated. Field-emission is also increased as the electric field increased by controllably reducing the height of the vacuum gap. Here we will explore the fabrication of vacuum hot electron light assisted cathodes (VHELACs).