Open AccessMany-body effects in doped WS2 monolayer quantum disks at room temperature
Author(s) -
Tzu-Jen Lin,
Svette Reina Merden Santiago,
Septem P. Caigas,
ChiTsu Yuan,
TaiYuan Lin,
JiLin Shen,
Y. F. Chen
Publication year - 2019
Publication title -
npj 2d materials and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.91
H-Index - 28
ISSN - 2397-7132
DOI - 10.1038/s41699-019-0129-z
Subject(s) - exciton , binding energy , monolayer , quantum dot , condensed matter physics , biexciton , renormalization , band gap , physics , potential well , materials science , atomic physics , nanotechnology , quantum mechanics
Due to strong Coulomb interactions, reduced screening effects, and quantum confinement, transition-metal dichalcogenide (TMD) monolayer quantum disks (MQDs) are expected to exhibit large exciton binding energy, which is beneficial for the investigation of many-body physics at room temperature. Here, we report the first observations of room-temperature many-body effects in tungsten disulfide (WS 2 ) MQDs by both optical measurements and theoretical studies. The band-gap renormalization in WS 2 MQDs was about 250 ± 15 meV as the carrier density was increased from 0.6(±0.2) × 10 12 to 8.3(±0.2) × 10 12 cm −2 . We observed a striking exciton binding energy as large as 990 ± 30 meV at the lowest carrier density, which is larger than that in WS 2 monolayers. The huge exciton binding energy in WS 2 MQDs is attributed to the extra quantum confinement in the lateral dimension. The band-gap renormalization and exciton binding energies are explained using efficient reduced screening. On the basis of the Debye screening formula, the Mott density in WS 2 MQDs was estimated to be ~3.95 × 10 13 cm −2 . Understanding and manipulation of the many-body effects in two-dimensional materials may open up new possibilities for developing exciton-based optoelectronic devices.