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Gate Tunable Dark Trions in Monolayer WSe2

Journal Article · · Physical Review Letters
 [1];  [2];  [3];  [2];  [4];  [4];  [5];  [2]
  1. Univ. of California, Riverside, CA (United States); DOE/OSTI
  2. Univ. of California, Riverside, CA (United States)
  3. National High Magnetic Field Lab., Tallahassee, FL (United States); Florida State Univ., Tallahassee, FL (United States)
  4. National Inst. for Materials Science, Ibaraki (Japan)
  5. National High Magnetic Field Lab., Tallahassee, FL (United States)
Monolayer WSe2 is an intriguing material to explore dark exciton physics. We have measured the photoluminescence from dark excitons and trions in ultraclean monolayer WSe2 devices encapsulated by boron nitride. The dark trions can be tuned continuously between negative and positive trions with electrostatic gating. We reveal their spin-triplet configuration and distinct valley optical emission by their characteristic Zeeman splitting under a magnetic field. Here, the dark trion binding energies are 14–16 meV, slightly lower than the bright trion binding energies (21–35 meV). The dark trion lifetime (~1.3 ns) is two orders of magnitude longer than the bright trion lifetime (~10 ps) and can be tuned between 0.4 and 1.3 ns by gating. Such robust, optically detectable, and gate tunable dark trions may help us realize trion transport in two-dimensional materials.
Research Organization:
Florida State Univ., Tallahassee, FL (United States)
Sponsoring Organization:
USDOE; USDOE Office of Science (SC)
Grant/Contract Number:
FG02-07ER46451
OSTI ID:
1609905
Alternate ID(s):
OSTI ID: 1546287
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 2 Vol. 123; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Cited By (7)

Valley Phonons and Exciton Complexes in a Monolayer Semiconductor text January 2020
Electroluminescence from multi-particle exciton complexes in transition metal dichalcogenide semiconductors journal April 2019
Valley phonons and exciton complexes in a monolayer semiconductor journal January 2020
Probing and Manipulating Valley Coherence of Dark Excitons in Monolayer WSe 2 journal August 2019
Phonon-mediated intervalley relaxation of positive trions in monolayer WSe 2 journal October 2019
Energy Spectrum of Two-Dimensional Excitons in a Nonuniform Dielectric Medium journal September 2019
Valley-selective chiral phonon replicas of dark excitons and trions in monolayer WS e 2 journal October 2019

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