Understanding and controlling growth of 2-d materials remains a significant challenge. Expanding upon the earlier work, which correlated high quality growth to a very broad Bell-Shaped-Component (BSC) background in surface electron diffraction, in situ experiments were conducted to better understand the origin of the BSC. These experiments monitored the BSC and the graphene reflection spot, Gr(10), with annealing temperature as graphene grew on SiC. The evolution of the BSC follows closely the increase of the Gr(10) diffracted intensity, direct proof that the BSC is an excellent diagnostic of the quality of graphene. Dysprosium metal intercalation and deposition experiments provide more information about the BSC. The BSC increases with metal intercalation, because a more uniform interface forms as the metal atoms move between graphene and SiC. These experiments support the conclusion that the BSC originates from electron confinement within a single layer material. This is an unusually strong manifestation of the uncertainty principle in mesoscale experiments. Utilizing the fundamental underlying physics discovered, it follows that the BSC should be a good diagnostic for optimizing the synthesis of other 2-d materials to insure single layer uniformity.
S. Chen, M. Horn von Hoegen, P. A. Thiel. A. Kaminski, B. Schrunk, T. Speliotis, E.H. Conrad and M.C.Tringides “High layer uniformity of 2-d materials surprisingly from broad features in surface electron diffraction” Journal of Physical Chemistry Letters J. Phys. Chem. Lett. 2020, 11, 8937−8943, https://dx.doi.org/10.1021/acs.jpclett.0c02113