High‐Speed Electroluminescence Modulation in Monolayer WS2

Abstract The high‐speed modulation of the nanoscale light sources is of fundamental interest in nanophotonics. Here, electrically driven light emission from a metal–insulator–semiconductor heterostructure consisting of graphene, hexagonal boron nitride (h‐BN), and monolayer tungsten disulfide (WS 2 ) is demonstrated. Electroluminescence in these devices originates from radiative recombination of majority carriers (electrons) accumulated by electrostatic doping and hot minority carriers (holes) injected into monolayer WS 2 from graphene through an ultrathin h‐BN tunnel barrier. The devices are electrically driven with a radio frequency signal and electrical modulation of the light emission at frequencies up to 1.5 GHz is demonstrated. The high‐speed WS 2 tunnel diodes provide a promising path for on‐chip nanophotonics.