Crystallographic dependence of adhesion energy of chemical vapor deposition–grown monolayer graphene on copper foils

Abstract

Chemical vapor deposition (CVD) is a widely used method for synthesizing large-area, high-quality monolayer graphene on metal substrates, particularly Cu. Although graphene transfer and manufacturing inevitably depend on interfacial interactions between graphene and seed Cu, the nature of polycrystalline Cu limits the ability to isolate the intrinsic adhesion characteristics of graphene. In this study, the effect of the crystallographic orientation of seed Cu foils on the adhesion energy of monolayer graphene was investigated through mesoscale mode I fracture tests using a double cantilever beam configuration. In addition to polycrystalline Cu foils, single-crystal Cu(111) and Cu(100) foils were prepared via an abnormal grain growth approach using high-temperature thermal annealing. Monolayer graphene was grown on those Cu foils using low-pressure CVD. Mechanical delamination of graphene from Cu revealed the adhesion energy of graphene to the underlying Cu: single-crystal Cu(111)-grown graphene exhibited a lower adhesion energy of 4.08 ± 0.68 J/m², compared with Cu(100)-grown graphene (6.71 ± 0.86 J/m²). Polycrystalline Cu-grown graphene exhibited the highest adhesion energy (8.08 ± 0.56 J/m²), likely due to increased surface roughness caused by Cu grain boundaries. This study offers critical insights into the fundamental interfacial properties of CVD-grown graphene and highlights the importance of the seed metal selection for reliable, large-scale manufacturing of graphene-based devices.