Diameter-Governed Vertical Growth of Graphene-Skinned Cu Wires with Enhanced Thermal Stability

Abstract Owing to its superior electrical and thermal conductivity and low cost, copper (Cu) is essential in power, communications, and electronics. However, ongoing device miniaturization poses critical challenges to its ampacity and environmental stability. In this study, vertical graphene-skinned Cu wires of 18 μm, 500 μm, and 1 mm in diameter were prepared using a solid carbon source without additional heating. The distinct graphene morphologies on Cu wires of different diameters stemmed from their dissimilar thermal responses and the effect of exposed catalytic area on growth. The growth process and structural characteristics of vertical graphene on 18 μm Cu wires were then investigated. Compared to horizontal graphene, vertical graphene offers superior oxidation resistance. While preserving the electrical performance of the Cu wires, vertical graphene enhances their thermal stability and current-carrying capacity. This work provides a coating strategy that integrates conductivity, heat dissipation, and durability for micro-wire protection in harsh environments.