Morphology Deformation and Giant Electronic Band Modulation in Long-Wavelength WS2 Moiré Superlattices

Kaihui Li; Feiping Xiao; Wen Guan; Yulong Xiao; Chang Xu; Jinding Zhang; Chenfang Lin; Dong Li; Qingjun Tong; Si-Yu Li; Anlian Pan

doi:10.1021/acs.nanolett.2c02418

Morphology Deformation and Giant Electronic Band Modulation in Long-Wavelength WS₂ Moiré Superlattices

Nano Lett. 2022 Jul 27;22(14):5997-6003. doi: 10.1021/acs.nanolett.2c02418. Epub 2022 Jul 15.

Authors

Kaihui Li^{1

2}, Feiping Xiao³, Wen Guan^{1

2}, Yulong Xiao^{1

2}, Chang Xu^{1

2}, Jinding Zhang^{1

2}, Chenfang Lin^{1

2}, Dong Li^{1

2}, Qingjun Tong³, Si-Yu Li^{1

2}, Anlian Pan^{1

2}

Affiliations

¹ Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, College of Materials Science and Engineering, Hunan University, Changsha 410082, People's Republic of China.
² Hunan Institute of Optoelectronic Integration, Hunan University, Changsha 410082, People's Republic of China.
³ School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China.

PMID: 35839083
DOI: 10.1021/acs.nanolett.2c02418

Abstract

As a lattice interference effect, moiré superlattices feature a magnification effect that they respond sensitively to both the extrinsic mechanical perturbations and intrinsic atomic reconstructions. Here, using scanning tunneling microscopy and spectroscopy, we observe that long-wavelength WS₂ superlattices are reconstructed into various moiré morphologies, ranging from regular hexagons to heavily deformed ones. We show that a dedicated interplay between the extrinsic nonuniform heterostrain and the intrinsic atomic reconstruction is responsible for this interesting moiré structure evolution. Importantly, the interplay between these two factors also introduces a local inhomogeneous intralayer strain within a moiré. Contrary to the commonly reported electronic modulation that occurred at the valence band edge due to interlayer hybridization, we find that this local intralayer strain induces a strong modulation at K point of the conduction band, reaching up to 300 meV in the heavily deformed moiré. Our microscopic explorations provide valuable information in understanding the intriguing physics in TMD moirés.

Keywords: atomic reconstruction; heterostrain; moiré superlattice; scanning tunneling microscopy; scanning tunneling spectroscopy; transition metal dichalcogenides.