Auger Recombination in Chemical Vapor Deposition-Grown Monolayer WS₂

Abstract

Reduced dimensionality and strong Coulombic interactions in monolayer semiconductors lead to enhanced many-body interactions. Here, we report Auger recombination, i.e., exciton-exciton annihilation, in large-area chemical vapor deposition-grown monolayer WS₂. Using ultrafast spectroscopy, we experimentally determine the Auger rate to be 0.089 ± 0.001 cm²/s at room temperature, which is an order of magnitude greater than the bulk value. This nonradiative recombination pathway dominates, regardless of excitation energy, for exciton densities greater than 8.0 ± 0.6 × 10¹⁰ cm^-2 and below the Mott density. Higher-energy excitation above the A exciton resonance may initially produce a hot electron-hole gas that precedes exciton formation. Therefore, we use resonant excitation of the A exciton to ensure accuracy and avoid artifacts associated with other photogenerated species.