Project Summary: Azimuthal reflection high-energy electron diffraction (ARHEED) is demonstrated as a powerful technique to measure the symmetry, lattice constants and in-plane orientation domain dispersion in wafer-scale, continuous monolayer WSe2 epitaxially grown on c-plane sapphire by metalorganic chemical vapor deposition. The constructed 2D reciprocal map from ARHEED reveals a few degrees’ dispersion in the 60o WSe2 orientation domains which is attributed to step meandering/bunching of the sapphire substrate. Minor 30o orientation domains are also observed. The angular domain dispersion accompanying the growth of finite domain size can be minimized by controlling the step structure of the sapphire substrate to reduce step meandering/bunching. Published in: Appl. Surf. Sci. 2021, 567, 150798.
2DCC Role: The wafer-scale WSe2 monolayer film on sapphire analyzed in this study was grown by MOCVD in the 2DCC-MIP Thin Films facility.
What Has Been Achieved: Characterization of orientation and domain dispersions in wafer-scale epitaxial WSe2 monolayers using azimuthal reflection high-energy electron diffraction (ARHEED).
Importance of the Achievement: ARHEED is demonstrated as a powerful technique to measure the symmetry, lattice constant and in-plane orientation domain dispersion in ultra-thin epitaxial TMD layers grown on sapphire.
Unique Feature(s) of the MIP that Enabled this Achievement: Wafer-scale WSe2 monolayers grown on c-plane sapphire by MOCVD in the 2DCC Thin Films facility.
(If Applicable) Publication:
X. Chen, B. Huet, T.H. Choudhury, J.M. Redwing, T.M. Lu and G.C. Wang, “Orientation domain dispersions in wafer scale epitaxial monolayer WSe2 on sapphire,” App. Surf. Sci. 2021, 567, 150798.
This work is supported by the New York State’s Empire State Development’s Division of Science, Technology and Innovation (NYSTAR) through Focus Center Contract C150117, Rensselaer, and the Penn State 2D Crystal Consortium - Materials Innovation Platform under National Science Foundation cooperative agreement DMR-1539916.