Crystal Orientation Dependent Oxidation Modes at the Buried Graphene-Cu Interface

We combine spatially resolved scanning photoelectron spectroscopy with confocal Raman and optical microscopy to reveal how the oxidation of the buried graphene-Cu interface relates to the Cu crystallographic orientation. We analyze over 100 different graphene covered Cu (high and low index) orientations exposed to air for 2 years. Four general oxidation modes are observed that can be mapped as regions onto the polar plot of Cu surface orientations. These modes are (1) complete, (2) irregular, (3) inhibited, and (4) enhanced wrinkle interface oxidation. We present a comprehensive characterization of these modes, consider the underlying mechanisms, compare air and water mediated oxidation, and discuss this in the context of the diverse prior literature in this area. This understanding incorporates effects from across the wide parameter space of 2D material interface engineering, relevant to key challenges in their emerging applications, ranging from scalable transfer to electronic contacts, encapsulation, and corrosion protection.