Electronic Tuning in WSe<sub>2</sub>/Au via van der Waals Interface Twisting and Intercalation.

Wu, Qilong; Bagheri Tagani, Meysam; Zhang, Lijie; Wang, Jing; Xia, Yu; Zhang, Li; Xie, Sheng-Yi; Tian, Yuan et al. · ACS Nano · 2022

basic_science · Level V

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Abstract

The transition metal dichalcogenide (TMD)-metal interfaces constitute an active part of TMD-based electronic devices with optimized performances. Despite their decisive role, current strategies for nanoscale electronic tuning remain limited. Here, we demonstrate electronic tuning in the WSe<sub>2</sub>/Au interface by twist engineering, capable of modulating the WSe<sub>2</sub> carrier doping from an intrinsic p-type to n-type. Scanning tunneling microscope/spectroscopy gives direct evidence of enhanced interfacial interaction induced doping in WSe<sub>2</sub> as the twist angle with respect to the topmost (100) lattice of gold changing from 15 to 0°. Taking advantage of the strong coupling interface achieved this way, we have moved a step further to realize an n-p-n-type WSe<sub>2</sub> homojunction. The intrinsic doping of WSe<sub>2</sub> can be recovered by germanium intercalation. Density functional theory calculations confirm that twist angle and intercalation-dependent charge transfer related doping are involved in our observations. Our work offers ways for electronically tuning the metal-2D semiconductor interface.