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

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 angstrom, 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.

Automated summary

In this study, a buckled GaN monolayer was obtained at the graphene/SiC interface under confinement using metal-organic chemical vapor deposition (MOCVD). Conductive atomic force microscopy (C-AFM) and scanning transmission electron microscopy (S/TEM) were used for characterization. The experiment confirmed the buckling parameter and revealed the atomic order of the GaN monolayer, providing new insights for predictive studies based on first-principles calculations.