Carrier losses due to radiative- and Auger-recombination in monolayer TMDCs

The intrinsic processes that fundamentally limit the lifetimes of carriers that are not bound in excitonic states are calculated for monolayer transition metal dichalcogenides (ML-TMDC). Radiative carrier lifetimes due to spontaneous recombination and emission of corresponding photoluminescence (PL) are calculated using the fully microscopic semiconductor luminescence equations. Here, it is shown that higher order excitonic correlations beyond bound excitons dramatically in uence the radiative recombination. These correlations are shown to enhance the PL and, correspondingly, decrease the radiative carrier lifetime by about one order of magnitude while dramatically changing the PL line-shape. Carrier recombinations due to free-carrier Auger-Meitner recombinations (AMR) are calculated solving the corresponding quantum-Boltzmann type scattering equations. The strong bandgap renormalizations on the order of several 100 meV are shown to lead to signi cant deviations from the classical scaling of the AMR lifetime with the inverse square of the free carrier density. Despite the far stronger Coulomb interaction in the ML-TMDC, the radiative and AMR lifetimes are found to be of similar magnitude as in more traditional III-V materials for similar operating wavelengths. Losses as function of the density and temperature are studied for MoS2, MoSe2, MoTe2, WS2 and WSe2 in various dielectric environments.