Interfacial Thermal Conductance between Cu and Diamond with Interconnected W-W₂C Interlayer

Manipulating the interfacial structure is vital to enhancing the interfacial thermal conductance (G) in Cu/diamond composites for promising thermal management applications. An interconnected interlayer is frequently observed in Cu/diamond composites; however, the G between Cu and diamond with an interconnected interlayer has not been addressed so far and thus is attracting extensive attention in the field. In this study, we designed three kinds of interlayers between a Cu film and a diamond substrate by magnetron sputtering coupled with heat treatment, including a W interlayer, an interconnected W-W₂C interlayer, and a W₂C interlayer, to comparatively elucidate the relationship between the interfacial structure and the interfacial thermal conductance. For the first time, we experimentally measured the G between Cu and diamond with an interconnected interlayer by a time-domain thermoreflectance technique. The Cu/W-W₂C/diamond structure exhibits an intermediate G value of 25.8 MW/m² K, higher than the 19.9 MW/m² K value for the Cu/W₂C/diamond structure and lower than the 29.4 MW/m² K value for the Cu/W/diamond structure. The molecular dynamics simulations show that the G of the individual W₂C/diamond interface is much higher than those of the individual Cu/diamond and W/diamond interfaces and W₂C could reduce the vibrational mismatch between Cu and diamond; however, the G of the Cu/W₂C/diamond structure is reduced by the lower thermal conductivity of W₂C. This study provides insights into the relationship between the interconnected interfacial structure and the G between Cu and diamond and offers guidance for interface design to improve the thermal conductivity in Cu/diamond composites.