Twist angle-dependent resonant tunneling electron transfer in WS/WSe/MoSe heterostructures.

Twisted van der Waals heterostructures formed by stacking monolayer materials offer a simple and exciting platform in condensed matter physics, where many novel physical effects have been observed. In the present work, a twist angle-dependent resonant tunneling electron transfer (RTET) effect, which was verified by giant quenching of WS photoluminescence (PL), is found in the WS/WSe/MoSe heterostructures (HS) by using PL measurements. Two types of interlayer excitons (IXs) are clearly observed, and the PL spectra measured under different excitations imply that charge transfer was a main contributor to the visibility of IXs. The samples with different stacking schemes are fabricated, and their PL spectra verified that the RTET from the conduction band of WS to the conduction band of MoSe is strongly dependent on the twist angle of WS/WSe/MoSe HS. The band alignment of WS/WSe/MoSe HS is calculated by using density functional theory (DFT) to support the RTET effect. Furthermore, the relationship between RTET and twist angles can be well-described by a quantum tunneling model. The efficiency of tunneling is actually related to momentum conservation in K-space. Our results provide additional insight into understanding the physics of IX and the process of charge transfer in twisted trilayer HS.