Effect of Electron Irradiation on the Transport and Field Emission Properties of Few-Layer MoS2 Field-Effect Transistors

Electrical characterization of few-layer MoS2-based field-effect transistors with Ti/Au electrodes is performed in the vacuum chamber of a scanning electron microscope in order to study the effects of electron-beam irradiation on the transport properties of the device. A negative threshold voltage shift and a carrier mobility enhancement are observed and explained in terms of positive charges trapped in the SiO2 gate oxide, during the irradiation. The transistor channel current is increased up to 3 orders of magnitudes after the exposure to an irradiation dose of 100 e−/nm2. Finally, a complete field emission characterization of the MoS2 flake, achieving emission stability for several hours and a minimum turn-on field of ≈20 V/μm with a field enhancement factor of about 500 at an anode−cathode distance of ∼1.5 μm, demonstrates the suitability of few-layer MoS2 as a two-dimensional emitting surface for cold-cathode applications.