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, WSe2/MoSe2, 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 × 1014 cm−2 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.
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机译:控制二维(2D)材料中的电荷密度是设计新的电子相和特性的有效方法。传统上,这种控制是通过静电门控来实现的。在这里,我们报告了一种使用过渡金属二卤化硅异质双分子层(WSe2 / MoSe2)和II型能带对准来生成高载流子密度的光学方法。通过将光激发密度调整到高于Mott阈值,我们实现了从层间激子到电荷分离的电子/空穴等离子体的相变,其中光激发电子和空穴被局限在各个层上。在脉冲和连续波激发条件下,都可以维持高达4×10 14 sup> cm -2 sup>的高载流子密度。这些发现为2D异质双分子层中电子相的光学控制打开了大门。
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