Size- and temperature-dependent thermal transport across a Cu−diamond interface: Non-equilibrium molecular dynamics simulations

Cu−diamond composites (CDCs) have greatly promising applications in thermal management for high-power electronics because of their outstanding thermophysical properties. Nonetheless, many fundamental mechanisms of interfacial thermal transport for CDCs remain poorly understood at present. Here we focus on investigating the size- and temperature-dependent thermal transport across a Cu−diamond interface using non-equilibrium molecular dynamics simulations. Results show that interfacial thermal conductance (ITC) is proportional to both the system size and ambient temperature. Especially, our predicted room-temperature ITC of 41.12 MW⋅m⁻²⋅K⁻¹ at an infinitely long system is close to that of the experiments after an interface optimization. Additionally, the ITC at the system with a length of 323.2 Å is increased by over 2.5 times in the temperature range of 100−500 K, up to 36.39 MW⋅ m⁻²⋅ K⁻¹. Detailed analyses of interfacial disorder and its concomitant effects, related to system size and temperature, are implemented for helping understand the significant improvement of ITC. The underlying mechanism is further uncovered by the phonon density of states as well as the spectral overlap factor at interfacial Cu and diamond. This study provides an important insight into the understanding of interfacial thermal transport in CDCs and a guideline for optimizing the design of CDCs in experiments.