TY - JOUR
T1 - Scalable Characterization of 2D Gallium-Intercalated Epitaxial Graphene
AU - El-Sherif, Hesham
AU - Briggs, Natalie
AU - Bersch, Brian
AU - Pan, Minghao
AU - Hamidinejad, Mahdi
AU - Rajabpour, Siavash
AU - Filleter, Tobin
AU - Kim, Ki Wook
AU - Robinson, Joshua
AU - Bassim, Nabil D.
N1 - Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/11/24
Y1 - 2021/11/24
N2 - Scalable synthesis of two-dimensional gallium (2D-Ga) covered by graphene layers was recently realized through confinement heteroepitaxy using silicon carbide substrates. However, the thickness, uniformity, and area coverage of the 2D-Ga heterostructures have not previously been studied with high-spatial resolution techniques. In this work, we resolve and measure the 2D-Ga heterostructure thicknesses using scanning electron microscopy (SEM). Utilizing multiple correlative methods, we find that SEM image contrast is directly related to the presence of uniform bilayer Ga at the interface and a variation of the number of graphene layers. We also investigate the origin of SEM contrast using both experimental measurements and theoretical calculations of the surface potentials. We find that a carbon buffer layer is detached due to the gallium intercalation, which increases the surface potential as an indication of the 2D-Ga presence. We then scale up the heterostructure characterization over a few-square millimeter area by segmenting SEM images, each acquired with nanometer-scale in-plane resolution. This work leverages the spectroscopic imaging capabilities of SEM that allows high-spatial resolution imaging for tracking intercalants, identifying relative surface potentials, determining the number of 2D layers, and further characterizing scalability and uniformity of low-dimensional materials.
AB - Scalable synthesis of two-dimensional gallium (2D-Ga) covered by graphene layers was recently realized through confinement heteroepitaxy using silicon carbide substrates. However, the thickness, uniformity, and area coverage of the 2D-Ga heterostructures have not previously been studied with high-spatial resolution techniques. In this work, we resolve and measure the 2D-Ga heterostructure thicknesses using scanning electron microscopy (SEM). Utilizing multiple correlative methods, we find that SEM image contrast is directly related to the presence of uniform bilayer Ga at the interface and a variation of the number of graphene layers. We also investigate the origin of SEM contrast using both experimental measurements and theoretical calculations of the surface potentials. We find that a carbon buffer layer is detached due to the gallium intercalation, which increases the surface potential as an indication of the 2D-Ga presence. We then scale up the heterostructure characterization over a few-square millimeter area by segmenting SEM images, each acquired with nanometer-scale in-plane resolution. This work leverages the spectroscopic imaging capabilities of SEM that allows high-spatial resolution imaging for tracking intercalants, identifying relative surface potentials, determining the number of 2D layers, and further characterizing scalability and uniformity of low-dimensional materials.
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U2 - 10.1021/acsami.1c14091
DO - 10.1021/acsami.1c14091
M3 - Article
C2 - 34780159
AN - SCOPUS:85119995837
SN - 1944-8244
VL - 13
SP - 55428
EP - 55439
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 46
ER -