Ambipolar Plasmon-Enhanced Photodetector Built on Germanium Nanodots Array/Graphene Hybrid

Graphene with gate-tunable electronic properties is promising as the channel materials in ambipolar multifunctional photodetectors. However, owing to the zero bandgap and weak light absorption, photodetectors fabricated on pristine graphene have low photoresponsivity. Herein, an ambipolar multifunctional photodetector with improved photocurrent and response speed is constructed on germanium (Ge) nanodots array-decorated graphene. The photocurrent map and simulated electric field distributions reveal that the enhanced photo-response is attributed to the localized surface plasmonic resonance effects by trapping light around the Ge nanodots. The photodetector exhibits ambipolar photo-response and the photocurrents can be tuned from negative to positive by applying different gate voltages due to the gate-tunable Fermi level of graphene. This ambipolar photodetector with fast response has excellent potential in imaging and sensing arrays as well as multifunctional photodetectors.