arXiv 2108.135732021-08-31cond-mat.mtrl-sci

MoS2/WS2异质双层膜中应变调制的层间电荷和能量转移

Strain-Modulated Interlayer Charge and Energy Transfers in MoS2/WS2 Heterobilayer

Joon-Seok Kim, Nikhilesh Maity, Myungsoo Kim, Suyu Fu, Rinkle Juneja, Abhishek K. Singh, Deji Akinwande, Jung-Fu Lin

摘要：

二维异质双分子层中的激子性质与范德华界面处的电荷转移（CT）和激子能量转移（ET）密切相关。已经采用了各种手段来调制层间CT和ET，包括电选通和修改层间间距，但其可控性程度有限。在这里，我们报告了一种新的方法来调制这些转移在MoS 2/WS 2异质双层通过在静水压力下施加压缩应变。拉曼和光致发光测量，结合密度泛函理论计算表明，压力增强的异质双层的层间相互作用。在异质双层中，WS 2的光致发光增强因子η在~ 4GPa时降低了5倍，表明具有强的ET，而在更高的压力下，它增加了一个数量级，并几乎达到1，表明CT增强。理论计算表明，在导带的轨道开关是负责调制的转移。我们的研究结果提供了一个令人信服的方法，有效的机械控制CT和ET在2D激子设备。

英文摘要：

Excitonic properties in 2D heterobilayers are closely governed by charge transfer (CT) and excitonic energy transfer (ET) at van der Waals interfaces. Various means have been employed to modulate the interlayer CT and ET, including electrical gating and modifying interlayer spacing, but with limited extent in their controllability. Here, we report a novel method to modulate these transfers in MoS2/WS2 heterobilayer by applying compressive strain under hydrostatic pressure. Raman and photoluminescence measurements, combined with density functional theory calculations show pressure-enhanced interlayer interaction of the heterobilayer. Photoluminescence enhancement factor η of WS2 in heterobilayer decreases by five times up to ~4 GPa, suggesting a strong ET, whereas it increases by an order of magnitude at higher pressures and reaches almost unity, indicating enhanced CT. Theoretical calculations show that orbital switching in the conduction bands is responsible for the modulation of the transfers. Our findings provide a compelling approach towards effective mechanical control of CT and ET in 2D excitonic devices.

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