Fig. 3: Radiative decay of tunnelling-induced excitons.
From: Exciton-assisted electron tunnelling in van der Waals heterostructures
a, Optical microscope image of a MoSe2 device fabricated on a glass (SiO2) substrate. The device consists of a vertical stack of a top hBN (t-hBN) protection layer, a MoSe2 monolayer, a graphene (Gr) monolayer, a ~3.3-nm-thick tunnel hBN layer (tnl-hBN) and a Au electrode. The graphene/hBN/Au tunnel junction is indicated by the white dashed line, where the graphene is partially covered by a MoSe2 monolayer (red polygon) on top. The upper two electrodes on the left serve as electrical contacts to the graphene sheet. Scale bar, 10 μm. b, Image of light emitted from the device at an applied voltage of 2.5 V, superimposed on the reference image of the device taken with back illumination. Scale bar, 10 μm. c, EL spectra for different bias voltages. The exciton peak at ~1.57 eV becomes more pronounced with increasing bias voltage.
