Strain distributions and their influence on electronic structures of WSe2–MoS2 laterally strained heterojunctions

• Published in: Nature nanotechnology Vol. 13; no. 2; pp. 152 - 158
• Main Authors: Zhang, Chendong, Li, Ming-Yang, Tersoff, Jerry, Han, Yimo, Su, Yushan, Li, Lain-Jong, Muller, David A., Shih, Chih-Kang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2018; Nature Publishing Group
• Subjects: 639/301/357/1018; 639/925/930/328/968; Alignment; Chemistry and Materials Science; Dislocations; Electronic properties; Electronic structure; Heterojunctions; Materials Science; Molybdenum disulfide; Nanotechnology; Nanotechnology and Microengineering; Optoelectronics; P-n junctions; Scanning transmission electron microscopy; Scanning tunneling microscopy; Spatial discrimination; Spatial resolution; Spectroscopy; Strain distribution; Transmission electron microscopy
• ISSN: 1748-3387; 1748-3395; 1748-3395
• DOI: 10.1038/s41565-017-0022-x

Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p–n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe 2 –MoS 2 , offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe 2 –MoS 2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe 2 –MoS 2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding. Mapping a moiré pattern in a lateral lattice-mismatched WSe 2 –MoS 2 heterojunction enables determination of the full strain tensor and the study of strain-induced electronic properties.