2D graphitic-like gallium nitride and other structural selectivity in confinement at the graphene/SiC interface

Sfuncia, Gianfranco and Nicotra, Giuseppe and Giannazzo, Filippo and Pécz, Béla and Gueorguiev, Gueorgui Kostov and Kakanakova-Georgieva, Anelia (2023) 2D graphitic-like gallium nitride and other structural selectivity in confinement at the graphene/SiC interface. CRYSTENGCOMM. ISSN 1466-8033

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Abstract

An atomic resolution image of an intercalated structure at a graphene/SiC interface along the growth direction which is determined as a buckled GaN monolayer at the immediate interface with an underlying SiC substrate and ultrathin Ga 2 O 3 on top. | Beyond the predictions routinely achievable by first-principles calculations and using metal–organic chemical vapor deposition (MOCVD), we report a GaN monolayer in a buckled geometry obtained in confinement at the graphene/SiC interface. Conductive atomic force microscopy (C-AFM) was used to investigate vertical current injection across the graphene/SiC interface and to establish the uniformity of the intercalated regions. Scanning transmission electron microscopy (S/TEM) was used for atomic resolution imaging and spectroscopy along the growth direction. The experimentally obtained value of the buckling parameter, 1.01 ± 0.11 Å, adds to the existing knowledge of buckled GaN monolayers, which is based solely on predictive first-principles calculations. Our study reveals a discontinuity in the anticipated stacking sequence attributed to a few-layer graphitic-like GaN structure. Instead, we identify an atomic order suggestive of ultrathin gallium oxide Ga2O3, whose formation is apparently mediated by dissociative adsorption of oxygen onto the GaN monolayer.

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