Dative Epitaxy of Commensurate Monocrystalline Covalent van der Waals Moiré Supercrystal

• Published in: Advanced materials (Weinheim) Vol. 34; no. 17; pp. e2200117 - n/a
• Main Authors: Bian, Mengying, Zhu, Liang, Wang, Xiao, Choi, Junho, Chopdekar, Rajesh V., Wei, Sichen, Wu, Lishu, Huai, Chang, Marga, Austin, Yang, Qishuo, Li, Yuguang C., Yao, Fei, Yu, Ting, Crooker, Scott A., Cheng, Xuemei M., Sabirianov, Renat F., Zhang, Shengbai, Lin, Junhao, Hou, Yanglong, Zeng, Hao
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.04.2022; Wiley
• Subjects: Chemical bonds; Chemical vapor deposition; commensurate lattices; Compatibility; Covalence; Crystal defects; Crystal growth; Crystal lattices; Crystal structure; dative bonds; Epitaxial growth; epitaxy; high magnetic field science; Hysteresis; Lattice matching; MATERIALS SCIENCE; Micrometers; Misalignment; moiré superlattices; Substrates; Superlattices; Thin films; van der Waals interaction; commensurate lattices; dative bonds; van der Waals interaction; epitaxy; moiré superlattices
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202200117

Realizing van der Waals (vdW) epitaxy in the 1980s represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here, the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition is reported, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few tens of micrometers, is fully commensurate with that of WSe2 via 3 × 3 (Cr5Te8)/7 × 7 (WSe2) supercell matching, forming a single‐crystalline moiré superlattice. This work establishes a conceptually distinct paradigm of thin‐film epitaxy, termed “dative epitaxy”, which takes full advantage of covalent epitaxy with chemical bonding for fixing the atomic registry and crystal orientation, while circumventing its stringent lattice matching and processing compatibility requirements; conversely, it ensures the full flexibility of vdW epitaxy, while avoiding its poor orientation control. Cr5Te8 2D crystals grown by dative epitaxy exhibit square magnetic hysteresis, suggesting minimized interfacial defects that can serve as pinning sites. Dative epitaxy represents the Goldilocks’ principle of epitaxy: it takes advantage of dative bonding for fixing the atomic registry and crystal orientation, while ensuring the full flexibility of van der Waals epitaxy. The globally commensurate Cr5Te8/WSe2 moiré supercrystal is distinctly different from conventional incommensurate moiré superlattices or local commensurate domains.