Electron over-barrier emission mechanism of single-layer graphene sheet

In this work, we investigate electron emission from vertically well-aligned single layer graphene inside a gap with an applied voltage. By considering electron traveling through an internal time-dependent potential barrier on the planar surface of the graphene sheet and then through an edge barrier, the current density is calculated. It is found that the over-barrier electron emission is the main mechanism and it is independent on the dc applied field. The current density can be controlled by a wide range of laser parameters, such as laser amplitude and frequency.