Riya Sebait1,2,Chandan Biswas2,Bumsub Song1,2,Changwon Seo1,2,Young Hee Lee1,2
Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS)1,Sungkyunkwan University2
Riya Sebait1,2,Chandan Biswas2,Bumsub Song1,2,Changwon Seo1,2,Young Hee Lee1,2
Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS)1,Sungkyunkwan University2
Unusually high exciton binding energies (BEs), as much as ∼1 eV in monolayer transition-metal dichalcogenides, provide opportunities for exploring exotic and stable excitonic many-body effects. These include many-body neutral excitons, trions, biexcitons, and defect-induced<br/>excitons at room temperature, rarely realized in bulk materials. Never-theless, the defect-induced trions correlated with charge screening have never been observed, and the corresponding BEs remain unknown. Here we report defect-induced A-trions and B-trions in monolayer tungsten disulfide (WS<sub>2</sub>) viacarrier screening engineering with photogenerated carrier modulation, external doping, and substrate scattering. Defect- nduced trions strongly couple with inherent SiO<sub>2</sub> hole traps under high photocarrier densities and become more prominent in rhenium-doped WS<sub>2</sub>. The absence of defect-induced trion peaks was confirmed using a trap-free hexagonal boron nitride substrate, regardless of power density . Moreover, many-body excitonic charge states and their BEs were compared via carrier screening engineering at room temperature. The highest BE was observed in the defect-induced A-trion state (∼214 meV), comparably higher than the trion (209 meV) and neutral exciton (174 meV), and further tuned by external photoinduced carrier density control. This investigation allows us to demonstrate defect-induced trion BE localization via spatial BE mapping in the monolayer WS<sub>2</sub> midflake regions distinctive from theflake edges.