Step engineering for nucleation and domain orientation control in WSe2 epitaxy on c-plane sapphire

• Published in: Nature nanotechnology Vol. 18; no. 11; pp. 1295 - 1302
• Main Authors: Zhu, Haoyue, Nayir, Nadire, Choudhury, Tanushree H., Bansal, Anushka, Huet, Benjamin, Zhang, Kunyan, Puretzky, Alexander A., Bachu, Saiphaneendra, York, Krystal, Mc Knight, Thomas V., Trainor, Nicholas, Oberoi, Aaryan, Wang, Ke, Das, Saptarshi, Makin, Robert A., Durbin, Steven M., Huang, Shengxi, Alem, Nasim, Crespi, Vincent H., van Duin, Adri C. T., Redwing, Joan M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2023; Nature Publishing Group
• Subjects: 140/133; 639/301/357/1018; 639/301/357/551; Chalcogenides; Chemistry and Materials Science; Epitaxial growth; Growth conditions; MATERIALS SCIENCE; Metalorganic chemical vapor deposition; Metals; Nanotechnology; Nanotechnology and Microengineering; Nucleation; Organic chemicals; Organic chemistry; Orientation; Sapphire; Single crystals; Substrates; Surface chemistry; Transition metal compounds
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-023-01456-6

Epitaxial growth of two-dimensional transition metal dichalcogenides on sapphire has emerged as a promising route to wafer-scale single-crystal films. Steps on the sapphire act as sites for transition metal dichalcogenide nucleation and can impart a preferred domain orientation, resulting in a substantial reduction in mirror twins. Here we demonstrate control of both the nucleation site and unidirectional growth direction of WSe 2 on c -plane sapphire by metal–organic chemical vapour deposition. The unidirectional orientation is found to be intimately tied to growth conditions via changes in the sapphire surface chemistry that control the step edge location of WSe 2 nucleation, imparting either a 0° or 60° orientation relative to the underlying sapphire lattice. The results provide insight into the role of surface chemistry on transition metal dichalcogenide nucleation and domain alignment and demonstrate the ability to engineer domain orientation over wafer-scale substrates. Surface chemistry controls the location of WSe 2 nucleation on a stepped sapphire substrate. Preferential nucleation at either the top or bottom step edge can be used to minimize mirror twin domains and produce unidirectional WSe 2 monolayers.