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Identifying Defect-Induced Trion in Monolayer WS2 via Carrier Screening Engineering
Identifying Defect-Induced Trion in Monolayer WS2 via Carrier Screening Engineering
- Source :
- ACS Nano. 15:2849-2857
- Publication Year :
- 2021
- Publisher :
- American Chemical Society (ACS), 2021.
-
Abstract
- 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 excitons at room temperature, rarely realized in bulk materials. Nevertheless, 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 (WS2) via carrier screening engineering with photogenerated carrier modulation, external doping, and substrate scattering. Defect-induced trions strongly couple with inherent SiO2 hole traps under high photocarrier densities and become more prominent in rhenium-doped WS2. 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 WS2 midflake regions distinctive from the flake edges.
- Subjects :
- Materials science
Exciton
Binding energy
Scanning tunneling spectroscopy
Doping
General Engineering
General Physics and Astronomy
02 engineering and technology
Substrate (electronics)
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
Molecular physics
0104 chemical sciences
Monolayer
General Materials Science
Trion
0210 nano-technology
Biexciton
Subjects
Details
- ISSN :
- 1936086X and 19360851
- Volume :
- 15
- Database :
- OpenAIRE
- Journal :
- ACS Nano
- Accession number :
- edsair.doi...........8d04e51d6c1ffe45eab3050327b9eef1
- Full Text :
- https://doi.org/10.1021/acsnano.0c08828