Structural identification of graphene films and nanoislands on 6H-SiC(0001) by direct height measurement

Hamza Ichou; Mohanad Alchaar; Bulent Baris; Adrien Michon; Roy Dagher; Erik Dujardin; David Martrou

doi:10.1088/1361-6528/acb2d0

Structural identification of graphene films and nanoislands on 6H-SiC(0001) by direct height measurement

Nanotechnology. 2023 Feb 9;34(16). doi: 10.1088/1361-6528/acb2d0.

Authors

Hamza Ichou¹, Mohanad Alchaar¹, Bulent Baris¹, Adrien Michon², Roy Dagher², Erik Dujardin¹, David Martrou¹

Affiliations

¹ Centre d'Élaboration de Matériaux et d'Études Structurales (CEMES), Université de Toulouse, 29 Rue J. Marvig, BP 94347, 31055 Toulouse Cedex, France.
² Université Côte d'Azur, CNRS, CRHEA, Valbonne F-06560, France.

PMID: 36638530
DOI: 10.1088/1361-6528/acb2d0

Abstract

By combining non-contact atomic force microscopy (nc-AFM) and Kelvin probe microscopy (KPFM) in ultra high vacuum environment (UHV), we directly measure the height and work function of graphene monolayer on the Si-face of 6H-SiC(0001) with a precision that allows us to differentiate three different types of graphene structures : zero layer graphene (ZLG), Quasi free-standing monolayer graphene (QFMLG) and bilayer graphene (BLG). The height and work function of ZLG are 2.62 ± 0.22 Å and 4.42 ± 0.05 eV respectively, when they are 4.09 ± 0.11 Å and 4.63 ± 0.05 eV for QFMLG. The work function is 4.83 ± 0.05 eV for the BLG. Unlike any other available technique, the local nc-AFM/KPFM dual probe makes it possible to directly identify the nature of nanometer-sized graphene islands that constitute the early nuclei of graphene monolayer grown on 6H-SiC(0001) by chemical vapor deposition.

Keywords: CVD graphene; UHV Kelvin probe force microscopy; UHV nc-AFM; quasi free-standing monolayer graphene (QFMLG); zero layer graphene (ZLG).