Figure 1. Tamm-monolayer device.

(a) Schematic illustration of the Tamm-plasmon device with the embedded WSe₂ monolayer. The monolayer is capped with PMMA, whose thickness primarily determines the frequency of the device's optical resonance. (b) PL spectrum of the WSe₂ monolayer before capping, recorded under ambient conditions. The dominant emission is identified to stem from the A-valley exciton. Inset: false-colour optical microscopy image of the used WSe₂ flake (monolayer in red shaded area; scale bar, 20 μm). (c) Calculation of the electromagnetic field intensity in the heterostructure and the optical resonance (inset). The Tamm-plasmon features a strongly enhanced field maximum close to the surface of the structure, which coincides with the vertical position of the monolayer in the device. The optical resonance features a quality factor on the order of 110.