Visualizing Band Profiles of Gate-Tunable Junctions in MoS<sub>2</sub>/WSe<sub>2</sub> Heterostructure Transistors
Xinzuo Sun, Yan Chen, Zhiwei Li, Yu Han, Qin Zhou, Binbin Wang, Takashi Taniguchi, Kenji Watanabe, Aidi Zhao, Jianlu Wang, Yuan Liu, Jiamin Xue
Abstract
Heterostructure devices based on two-dimensional materials have been under intensive study due to their intriguing electrical and optical properties. One key factor in understanding these devices is their nanometer-scale band profiles, which is challenging to obtain in devices. Here, we use a technique named contact-mode scanning tunneling spectroscopy to directly visualize the band profiles of MoS2/WSe2 heterostructure devices at different gate voltages with nanometer resolution. The long-held view of a conventional p–n junction in the MoS2/WSe2 heterostructure is reexamined. Due to strong inter- and intralayer charge transfer, the MoS2 layer in contact with WSe2 is found to convert from n-type to p-type, and a series of gate-tunable p–n and p–p+ junctions are developed in the devices. Highly conductive edges are also discovered which could strongly affect the device properties.