Electron Field Emission of Geometrically Modulated Monolayer Semiconductors

Electron field emission, electrons emitted from solid surfaces under high electric field, offers significant scientific interests in materials sciences and potential optoelectronics applications. 2D atomic layers, such as MoS2, exhibit fascinating properties for diverse applications in next-generation nanodevices and rich physical phenomena for fundamental research. However, the study on field emission of semiconducting monolayers is lacking owing to its low efficiency and stability of electron emission. Here, electron field emission of the geometrically modulated monolayer semiconductors suspended with 1D nanoarrays is demonstrated. Chemical vapor deposition synthesis of two prototype monolayers of transition metal dichalcogenides (TMD), MoS2 and MoSe2, is presented and their diverse band structures offer an ideal platform to explore the fundamental process of the electron emission in the TMD. Geometrical modulation and charge transfer of the semiconducting monolayers can be significantly tuned with the structural suspension with the 1D ZnO nanoarrays. Possible mechanisms on the enhanced electron emission of the 2D monolayers are discussed. With geometrical control of the monolayers, a highly efficient and stable electron emission of TMD monolayers is achieved in low turn-on electric fields, enabling applications on electrons sources and opening a new avenue toward geometrically tuned atomic layers.