Atomic Scale Depletion Region in a MoSe2-WSe2 Lateral Heterojunction
Yu-Hsun Chu1*, Li-Hong Wang1, Hou-Ju Chen1, Po-Ya Yang1, Christopher J. Butler1, Li-Syuan Lu2, Han Yeh2, Wen-Hao Chang2,3, Minn-Tsong Lin1,4,5
1Department of Physics, National Taiwan University, Taipei, Taiwan
2Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
3Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology, Taiwan
4Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
5Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
* presenting author:Yu-Hsun Chu,
Following the success of graphene, monolayer transition metal dichalcogenides (TMDCs) have become one of the most intriguing 2D materials. Wide element choices with different structures give TMDCs versatile properties; for example, 1H group VI (Mo and W) TMDCs, also called semiconducting analogues of graphene, possess distinct electron valleys with locked spin, which are full of potential in valleytronics and spintronics. Advanced heterosystems can be constructed by stitching TMDCs into lateral junctions, in which the 1D interfaces may induce new properties like boundary states and band alignments, and have been proved significant to optoelectronics.[1] Performing scanning tunneling microscopy (STM) and spectroscopy (STS) at room temperature, we resolved structuraland electronic properties at a 1D MoSe2-WSe2 heterointerface. Continuous lattice structures across the boundary without rotation and translation were confirmed from atomically mapped STM images. A narrow and symmetric depletion region within a few nanometers was observed at boundaries, indicative of high carrier concentration in the TMDC regions and a large built-in electric field. The investigations are essential to functions in lateral junctions such as carrier separation for optoelectronics, and reveal fundamentals of practical TMDC applications.

[1] C. Huang, X. Xu, et al., Nat. Mater. 13, 1096 (2014).

Keywords: Transition Metal Dichalcogenides, Scanning Tunneling Microscopy, Lateral Heterojunction, Heterointerface