Dependence of carbon nanotube array-silicon interface thermal conductance on array arrangement and filling fraction

Carbon nanotube (CNT) is a promising candidate of thermal interface material for micro/nano-scale devices due to its ultra-high axial thermal conductivity. However, low interface thermal conductance between CNT and other materials restricts its effectiveness in the thermal management. We use non-equilibrium molecular dynamics (NEMD) method to investigate the factors that possibly influence the interface thermal conductance between vertical CNT array and silicon substrate. The dependence of the interface thermal conductance on the arrangement of CNT (aligned and crossed), filling fraction (0.14-0.70), CNT diameter (6.88-35.75 Å), temperature (200-400 K), and van der Waals force among the CNTs are studied in detail. From the simulation results, the enhancement of the interface thermal conductance difference caused by CNT-array filling fraction in this work reaches to 91%, and that value caused by the arrangement of CNT on silicon is as high as 84%. The mechanism of heat transport across the interface between CNT array and silicon substrate is discussed by comparing the vibrational densities of states (VDOS) of atoms from both sides under different conditions.