Optical generation of high carrier densities in 2D semiconductor heterobilayers.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31548986.
- Also identified by DOI 10.1126/sciadv.aax0145 and PMC identifier 6744266.
- Licence recorded as CC BY-NC.
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Abstract
Controlling charge density in two-dimensional (2D) materials is a powerful approach for engineering new electronic phases and properties. This control is traditionally realized by electrostatic gating. Here, we report an optical approach for generation of high carrier densities using transition metal dichalcogenide heterobilayers, WSe<sub>2</sub>/MoSe<sub>2</sub>, with type II band alignment. By tuning the optical excitation density above the Mott threshold, we realize the phase transition from interlayer excitons to charge-separated electron/hole plasmas, where photoexcited electrons and holes are localized to individual layers. High carrier densities up to 4 × 10<sup>14</sup> cm<sup>-2</sup> can be sustained under both pulsed and continuous wave excitation conditions. These findings open the door to optical control of electronic phases in 2D heterobilayers.