Presentation Information
[23a-31B-5]Auger Annihilation of Interlayer Excitons in WS2/WSe2 Moiré Heterobilayers
〇Wei-Ting Hsu1, Cheng-Syuan Cai1,2, Wei-Yan Lai1, Po-Hsuan Liu1, Tzu-Chieh Chou1,2, Chih-Ming Lin1, Shangjr Gwo1, Ro-Ya Liu2 (1.Department of Physics, National Tsing Hua University, Taiwan, 2.National Synchrotron Radiation Research Center, Taiwan)
Keywords:
van der Waals bilayer,transition metal dichalcogenide,exciton-exciton interaction
Strong Coulomb interactions play a key role in determining the electronic and optical properties of transition metal dichalcogenide (TMD) heterobilayers. In particular, their type-II band alignment, combined with the moiré superlattice, inevitably leads to nontrivial exciton-exciton interactions. Here, we report distinct Auger annihilation processes for interlayer excitons in WS2/WSe2 moiré heterobilayers. By fitting the characteristic efficiency droop and bimolecular recombination rate, we report an ultralow Auger coefficient of the order of 10-5 cm2s-1, which is more than 100-fold smaller than excitons in TMD monolayers. We further report layer-selective exciton upconversion, which highlights the importance of intralayer electron scattering in dictating microscopic pathways.