Field Emission Control via Work Function Modulation in Semimetallic Graphene Edge Cathodes

ABSTRACT Graphene, the bandgapless 2D crystal, uniquely combines metal‐like conductivity with an electrostatically tunable Fermi level—an ability that conventional metals lack. Here, we exploit this semimetallic property to realize a vacuum edge emitter whose current can be directly modulated through work function control rather than relying on vacuum‐channel field reshaping. We demonstrate a graphene edge–emitter nanoscale vacuum transistor with an off‐channel gate, enabling spatial separation of emission and control fields and achieving current saturation and low‐voltage modulation across a 500 nm vacuum gap. This architecture minimizes interception and leakage while offering a structurally simple and scalable means of accessing direct Fermi‐level modulation at the emission site. The device shows stable Fowler–Nordheim tunneling from 10 to 300 K, with gate‐tunable emission onset and saturation current. Using small‐signal parameters extracted entirely from measured I – V data, we further illustrate, through numerical analysis, that the demonstrated device characteristics are consistent with amplification behavior when placed in canonical circuit topologies. More broadly, the direct work‐function modulation strategy provides a general pathway for precise control of vacuum electron emission, with potential relevance for RF, cryogenic, and radiation‐resilient electronic systems.