Direct Observation of Gate Tunable Dark Trions in Monolayer WSe2

Understand

Spin-forbidden intravalley dark exciton in tungsten-based transition metal dichalcogenides (TMDCs), owing to its unique spin texture and long lifetime, has attracted intense research interest.

• Here, we show that we can control the dark exciton electrostatically by dressing it with one free electron or free hole, forming the dark trions.
• The existence of the dark trions is suggested by the unique magneto-photoluminescence spectroscopy pattern of the boron nitride (BN) encapsulated monolayer WSe2 device at low temperature.
• The unambiguous evidence of the dark trions is further obtained by directly resolving the radiation pattern of the dark trions through back focal plane imaging.