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 & PLUSMN; 0.11 & ANGS;, 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. 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 Ga2O3 on top.

Automated summary

Beyond the predictions and calculations, a buckled GaN monolayer was obtained at the graphene/SiC interface through confinement conditions. The atomic resolution imaging revealed the atomic order and formation mechanism of the intercalated structure.