Science Daily May 15, 2020 When monolayer WSe2 absorbs a photon, a bound electron can be freed in a valley, leaving behind a hole resulting in an exiton. This is called an intravalley exciton which can emit light. The law of momentum conservation, however, forbids an electron and a hole in opposite valleys from recombining directly to emit light. As a result, intervalley excitons are “dark” and hidden in the optical spectrum. An international team of researchers (USA – UC Riverside, Taiwan, Japan) found that although the intervalley excitons are intrinsically dark, they can emit circularly polarized light. The optically […]
Tag Archives: Trions
Giving valleytronics a boost
Science Daily October 28, 2019 Development of valleytronics requires stable valley states and easy identification of the valley indices. An international team of researchers (USA- UC Riverside, Japan, Taiwan) have shown that dark excitons and trions in monolayer WSe2 have much longer lifetime and better valley stability than the common bright excitons and trions, therefore, serve as excellent candidates for valleytronic applications. Until now no method could read the valley indices of the dark excitons and trions because their light emission from either valley has exactly the same energy and polarization, making the two valleys indistinguishable from each other. They […]
Physicists’ finding could revolutionize information transmission
Phys.org July 9, 2019 An international team of researchers (USA – UC Riverside, National High Magnetic Field Laboratory, State University of Florida, Japan) has observed, characterized, and controlled dark trions in tungsten diselenide. Because a trion contains three interacting particles, controllable spin and momentum indices and a rich internal structure, it can carry much more information than a single electron. The lifetime of dark trions is more than 100 times longer than the more common bright trions. The long lifetime enables information transmission by trions over a much longer distance. They demonstrated continuous tuning from positive dark trions to negative […]