Understanding the thermal conductivity of Diamond/Copper composites by first-principles calculations

SThe present paper investigates the nanoscale thermal transport at diamond/copper (dCu) interfaces using the density functional theory (DFT) and the atomistic Green's function method. The DFT calculations show the boundary scattering become negligible for diamond particles larger than 10 μm. The temperature-dependent thermal conductivity of the dCu composite is predicted according to the thermal boundary conductance and thermal conductivity from DFT calculations. The results show a low thermal boundary conductance (18.5–26.9 MW/m2K at 300 K) at dCu interfaces causes the reduction in the thermal conductivity of dCu composites with small diamond particles or at low temperatures. Due to the dominant effects of interfacial resistance, adding small diamond particles (<16 μm) in a Cu matrix can only cause a reduction in the effective thermal conductivity of composites regardless of temperature. For diamond particles larger than 16 μm, the enhancement of effective thermal conductivity is most noticeable at relatively low temperatures (120 K ∼ 170 K), and thereafter the enhancement becomes smaller due to the decrease of the diamond thermal conductivity. The results provide insights to understand the mechanism of thermal transport at dCu interfaces and guidelines to engineer the thermal properties of dCu composites.