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Imaging and measuring the electronic properties of epitaxial graphene with a photoemission electron microscope

Published

Author(s)

Falk Niefind, Henry Bell, Thuc Mai, Angela R. Hight Walker, Randolph Elmquist, Sujitra Pookpanratana

Abstract

A photoemission electron microscope (PEEM) was recently commissioned at the NIST. To benchmark its capabilities, epitaxial graphene on 4H-SiC (0001) was imaged and analyzed in the PEEM and compared to other complementary imaging techniques. We determine our routine spatial resolution to be about 50 nm. Using the well-known electronic structure of graphene as a reference, we outline a procedure to calibrate our instrument in energy and momenta in the micrometer-angle-resolved photoemission spectroscopy (μ-ARPES). We also determine the energy and momenta resolution to be about 300 meV, 0.08 Å−1 (ky), and 0.2 Å−1 (kx), respectively. We identify distinct regions of the graphene surface based on intensity contrast rising from topographic and electronic contrasts as well as μ-ARPES. These regions are one layer graphene, one SiC buffer layer, and ≥2 layers of graphene (or graphite). These assignments are confirmed using confocal laser scanning microscopy and Raman spectroscopy. Finally, the PEEM instrument had enough sensitivity to observe the flatband in monolayer epitaxial graphene, which we attribute to the presence of compressive strain, −1.2%, in the graphene sample.
Citation
Journal of Applied Physics
Volume
131

Keywords

photoemission, photoemission electron microscopy, electron microscopy, graphene, band structure, ARPES

Citation

Niefind, F. , Bell, H. , Mai, T. , Hight Walker, A. , Elmquist, R. and Pookpanratana, S. (2022), Imaging and measuring the electronic properties of epitaxial graphene with a photoemission electron microscope, Journal of Applied Physics, [online], https://doi.org/10.1063/5.0076145, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933201 (Accessed March 30, 2023)
Created January 3, 2022, Updated November 29, 2022