Unveiling the optical emission channels of monolayer semiconductors coupled to silicon nanoantennas.

Monolayers (MLs) of transition metal dichalcogenides (TMDs) such as WSe2 and MoSe2 can be placed by dry stamping directly on broadband dielectric resonators, which have the ability to enhance the spontaneous emission rate and brightness of solid-state emitters at room temperature. We show strongly enhanced emission and directivity modifications in room temperature photoluminescence mapping experiments. By varying TMD material (WSe2 versus MoSe2) transferred on silicon nanoresonators with various designs (planarized versus non-planarized), we experimentally separate the different physical mechanisms that govern the global light emission enhancement. For WSe2 and MoSe2 we address the effects of Mie Resonances and strain in the monolayer. For WSe2 an important additional contribution comes from out-of-plane exciton dipoles. This paves the way for more targeted designs of TMD-Si nanoresonator structures for room temperature applications.