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.

κ, κ e , κ L , and T are the Seebeck coefficient, electrical conductivity, total thermal conductivity, electrical thermal conductivity, lattice thermal conductivity, and absolute working temperature, respectively. [1,2] Since α, σ, and κ are strongly coupled with each other, a simple improvement in single parameter usually results in a deterioration of the others. The challenge of realizing superior TE properties lies in the improvement of ZT, that is, simultaneously increasing in power factor (PF = α 2 σ) and suppressing κ. Normally, α enhancement can be achieved by a carrier energy filtering effect, caused by band bending at the nanointerfaces between nanoparticle and TE host materials. [2-4] Meanwhile, reducing κ L by phonon scattering is an effective way to reduce κ while maintaining a high σ. Very recently, lattice strains regulated by annealing time have also been observed for remarkably decreasing κ without affecting the carrier mobility (µ). [3] Sb 2 Te 3 and its derivatives are considered to be one of the best p-type TE materials near room temperature. [5] Compared with its bulk counterparts, nanostructured Sb 2 Te 3 film provides promising possibilities for enhanced TE properties and potential applications in micro/nanoelectromechanical systems (MEMS/NEMS) TE device. [6] Experimentally, Sb 2 Te 3 has been prepared by various approaches such as physical vapor deposition (PVD), solid state reaction, and chemical synthesis method and so on. [1,7,8] The effect of substrate, annealing temperature, and thickness on PF as well as the strain-and grain size-dependent κ in Sb 2 Te 3 films was studied. [9-11] PF can be enhanced by introducing nanoscale metal/semimetals into

The metal/diamond interface consisting of two highly dissimilar materials is widely present in high-power microelectronic devices using a diamond film as a heat spreader or using a metal matrix/diamond filler composite as a heat sink for thermal management applications. To improve the interfacial thermal conductance (G), a common method is to add an appropriate interlayer in between the two materials; however, the effect of the interlayer on G is still not clear. In this work, we prepare a Cu/TiC/diamond structure by magnetron sputtering to detect how the crystallinity, grain size, and thickness of the TiC interlayer influence G between Cu and diamond. We characterize in detail the interface by transmission electron microscopy and X-ray photoelectron spectroscopy and measure experimentally G by the time-domain thermoreflectance technique. The results indicate that the higher crystallinity and thinner interlayer are both beneficial to the improvement of G between Cu and diamond, but the G is insensitive to the grain size of TiC. An increase of G between Cu and diamond as much as 48% can be reached by a highly crystallized 10 nm thick TiC interlayer. The microscopic characteristics of the TiC interlayer have played a decisive role for G between Cu and diamond. While an inserted interlayer in principle has a potential to enhance G between two dissimilar materials, the low crystallinity and large thickness of the interlayer will weaken the enhancement or even reverse this positive effect. The G of a sandwiched structure can be regulated in a wide range by the microscopic characteristics of the interlayer, which provides guidelines for preparation of metal/nonmetal interfaces with high interfacial thermal conductance for thermal management applications.