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

doi:10.1038/s41565-023-01456-6

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

2023-07-27

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Tanushree H. Choudhury

Alexander A. Puretzky

DOI：10.1038/s41565-023-01456-6

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Surface chemistry controls the location of WSe2 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 WSe2 monolayers. 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 WSe2 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 WSe2 nucleation, imparting either a 0 & DEG; or 60 & DEG; 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.

Keywords:

TOTAL-ENERGY CALCULATIONS

ULTRASOFT PSEUDOPOTENTIALS

VALLEY POLARIZATION

GRAPHENE

GROWTH

MONOLAYERS

FIELD

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

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