Emission enhancement from MoS 2 monolayers with silicon nanoantennas

Transition-metal-dichalcogenides (TMDs), which exhibit an indirect electronic band gap as bulk crystals, can become direct semiconductors in the monolayer phase [1]. Such monolayer TMDs show unique optical properties arising from the strong two-dimensional confinement of excitons as well as from the reduction in crystal symmetry. However, the strong mismatch in length scale between the sub-nanometer thickness of an atomically thin crystal sheet and the wavelength of propagating infrared or visible light leads to a rather weak light-matter interaction. By tailoring the near-field environment of monolayer TMDs, resonant optical antennas can strongly modify the excitation response [2]. While research efforts targeted at tailoring and enhancing light-matter interactions in monolayer TMDs have so far been limited to plasmonic nanoantennas, here we concentrate on high-index dielectric nanoantennas, which can show negligible intrinsic losses and thus a high radiation efficiency in the visible and near-infrared spectral range.