Observation of intervalley transitions can boost valleytronic science and technology

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 readable valley configuration is crucial to making intervalley excitons useful for valleytronic applications. Monolayer WSe2 also hosts trions which have well-defined valley configurations for valleytronic applications. The research provides a more complete, multipath picture of trion dynamics in monolayer WSe2…read more. TECHNICAL ARTICLE 

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