Monolayer WSe₂ with a direct bandgap shows great application potential in photon–electronic devices. Using in situ angle-resolved photoemission spectroscopy, we investigate the interfacial charge transfer between the grown WSe₂ films and the graphene with different numbers of layers. For the WSe₂ grown on the monolayer graphene (MLG) substrate, its band structure shifts downward by ∼140 meV compared to that grown on the bilayer graphene (BLG) substrate and by ∼230 meV compared to that grown on trilayer graphene (TLG), revealing that the MLG substrate transfers more electrons to the grown WSe₂ than what the BLG and TLG do. Our results provide significant information for understanding the charge transfer behaviors and energy-level alignments in the two-dimensional (2D) stacking-heterostructures as well as the designation of future nano-devices based on 2D materials.

中文翻译：

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外延单层 WSe2film 和石墨烯衬底之间的电荷转移

具有直接带隙的单层 WSe ₂在光子电子器件中显示出巨大的应用潜力。使用原位角分辨光电子能谱，我们研究了生长的 WSe ₂薄膜和具有不同层数的石墨烯之间的界面电荷转移。对于在单层石墨烯 (MLG) 衬底上生长的 WSe ₂，与在双层石墨烯 (BLG) 衬底上生长的相比，其能带结构向下移动了 ~140 meV，与在三层石墨烯 (TLG) 上生长的相比，其能带结构向下移动了 ~230 meV ，表明 MLG 衬底将更多的电子转移到生长的 WSe ₂而不是 BLG 和 TLG 所做的。我们的结果为理解二维（2D）堆叠异质结构中的电荷转移行为和能级排列以及基于二维材料的未来纳米器件的设计提供了重要信息。