We report the observation and gate manipulation of intrinsic dark trions in monolayer WSe2. By using ultraclean WSe2 devices encapsulated by boron nitride, we directly resolve the weak photoluminescence of dark trions. The dark trions can be tuned continuously between negative and positive charged trions with electrostatic gating. We also reveal their spin triplet configuration and distinct valley optical emission by their characteristic Zeeman splitting under magnetic field. The dark trions exhibit large binding energy (14-16 meV). Their lifetime (~1.3 ns) is two orders of magnitude longer than the bright trion lifetime (~10 ps) and can be tuned between 0.4 to 1.3 ns by electrostatic gating. Such robust, optically detectable, and gate tunable dark trions provide a new path to realize electrically controllable trion transport in two-dimensional materials.
Cite
@article{arxiv.1901.11043,
title = {Gate tunable dark trions in monolayer WSe$_2$},
author = {Erfu Liu and Jeremiah van Baren and Zhengguang Lu and Mashael M. Altaiary and Takashi Taniguchi and Kenji Watanabe and Dmitry Smirnov and Chun Hung Lui},
journal= {arXiv preprint arXiv:1901.11043},
year = {2019}
}