Interlayer Excitons in WS₂/WSe₂ Moiré Heterobilayers: Distinct Auger Processes

Cheng-Syuan Cai^1,2, Wei-Yan Lai¹, Po-Hsuan Liu¹, Tzu-Chieh Chou^1,2, Ro-Ya Liu², Chih-Ming Lin¹, Shangjr Gwo¹, Wei-Ting Hsu^1*

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Wei-Ting Hsu, email:wthsu@phys.nthu.edu.tw

Strong electronic interactions, such as interlayer hybridization and exciton interaction, play a key role in determining electronic and optical properties of transition metal dichalcogenide (TMD) heterobilayers. In this context, their type-II band alignment, combined with the moiré superlattice, inevitably leads to nontrivial exciton interactions. Here, we report the distinct Auger processes for interlayer excitons in WS₂/WSe₂ moiré heterobilayers. The first is an ultralow Auger coefficient of 1.3×10^-5 cm² s^-1, which is more than 100-fold smaller than excitons in TMD monolayers. The second is layer-selective exciton upconversion, which highlights the significance of intralayer Coulomb interactions in dictating the microscopic scattering pathways.

Keywords: van der Waals bilayer, transition metal dichalcogenide, exciton-exciton interaction