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Enhanced exciton-exciton collisions in an ultra-flat monolayer MoSe2 prepared through deterministic flattening
- Source :
- ACS Nano 2020
- Publication Year :
- 2020
-
Abstract
- Squeezing bubbles and impurities out of interlayer spaces by applying force through a few-layer graphene capping layer leads to van der Waals heterostructures with ultra-flat structure free from random electrostatic potential arising from charged impurities. Without the graphene capping layer, a squeezing process with an AFM tip induces applied-force-dependent charges of n ~ 2 x 10^12 cm^-2 uN^-1, resulting in strong intensity of trions in photoluminescence spectra of MoSe2 at low temperature. We found that a hBN/MoSe2/hBN prepared with the "modified nano-squeezing method" shows a strong excitonic emission with negligible trion peak, and the residual linewidth of the exciton peak is only 2.2 meV, which is comparable to the homogeneous limit. Furthermore, in this high-quality sample, we found that formation of biexciton occurs even at extremely low excitation power (Phi ~ 2.3 x 10^19 cm^-2 s^-1) due to the enhanced collisions between excitons.
- Subjects :
- Condensed Matter - Mesoscale and Nanoscale Physics
Subjects
Details
- Database :
- arXiv
- Journal :
- ACS Nano 2020
- Publication Type :
- Report
- Accession number :
- edsarx.2006.02640
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1021/acsnano.0c08642