Interfacial Interaction and Stress Engineering for Enhancing Electrical Conductivity of Graphene/Copper Composites

Copper with electrical conductivity (EC) exceeding 100% International Annealed Copper Standard (IACS) is in high demand for power and microelectronic applications. Graphene/copper composites have emerged as a promising solution to meet this demand. However, the mechanism underlying the EC enhancement remains a subject of debate, which poses a challenge to their scalable production. In this study, we fabricated graphene/copper composite through plasma-enhanced chemical vapor deposition (PECVD) and demonstrated the enhanced EC up to 109.4% IACS by controlling the interfacial interaction between graphene and copper. Electron backscatter diffraction (EBSD) reveals directional residual stresses in the copper substrate, while high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA) resolve a near-surface lattice-distortion layer beneath a few layers continuous graphene. By tuning hydrogenation defects through RF power, we modulate interfacial adhesion, the induced stress state, and the EC enhancement. The results establish interfacial-stress engineering as a practical route to copper conductors surpassing 100% IACS.