Spot Profile Analysis Low Energy Electron Diffraction of Plasma-Enhanced Chemical Vapor Deposition Grown Epitaxial Few-Layer Graphene on Sapphire

Niels Ganser; Marko A. Kriegel; Umut Kaya; Jixi Zhang; Rodney D. L. Smith; Marika Schleberger; Wolfgang Mertin; Gerd Bacher; Michael Horn-von Hoegen

arXiv · 2607.14922

Spot Profile Analysis Low Energy Electron Diffraction of Plasma-Enhanced Chemical Vapor Deposition Grown Epitaxial Few-Layer Graphene on Sapphire

Niels Ganser·Marko A. Kriegel·Umut Kaya·Jixi Zhang·Rodney D. L. Smith·Marika Schleberger·Wolfgang Mertin·Gerd Bacher·Michael Horn-von Hoegen

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Abstract

We demonstrate the use of high-resolution spot-profile analysis low-energy electron diffraction to determine the mean grain size of plasma-enhanced chemical vapor deposition grown few-layer graphene on sapphire (Al$_2$O$_3$). The diffraction patterns exhibit broadened graphene spots, pronounced diffuse scattering, and azimuthally extended features, indicating finite crystallite size and rotational disorder. By analyzing the finite-size broadening of the specular (00) spot with an Airy-type diffraction profile, we determine a mean grain diameter of 3.7$\,$nm for the as-grown graphene layer. Post-growth annealing under ultrahigh-vacuum conditions increases the mean grain size to about 5.7$\,$nm and 6.8$\,$nm, respectively. These results establish SPA-LEED as a sensitive reciprocal-space method for quantifying the structural coherence of directly grown graphene on insulating substrates.

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Niels Ganser, Marko A. Kriegel, Umut Kaya, Jixi Zhang, Rodney D. L. Smith, Marika Schleberger, Wolfgang Mertin, Gerd Bacher, Michael Horn-von Hoegen. 2026-07-16. Spot Profile Analysis Low Energy Electron Diffraction of Plasma-Enhanced Chemical Vapor Deposition Grown Epitaxial Few-Layer Graphene on Sapphire. https://arxiv.org/abs/2607.14922

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