凯发

The increasing power density and the decreasing dimensions of transistors present severe thermal challenges to the design of modern microprocessors. Furthermore, new technologies such as three-dimensional chip stack architectures require novel cooling solutions for their thermal management. To address these problems, thermal properties of graphene and carbon nano tube have been subjects of intensive investigations. However, the large contact thermal resistance of CNTs and thelow c-axis thermal conductivity in few-layer graphene (FLG) present major roadblocks for their applications as thermal interface materials (TIMs). In this talk, I will present our recent progress on developing graphene based high-performance TIMs. By applying mechanical strain that can tailor the phonon spectrum, we demonstrate that the inter-layer thermal resistance in FLG can be reduced by 85%. Furthermore, we show that by replacing the inter-layer van der Waals interaction with the covalentsp2 bond with the CNT, the graphene-CNT(G-CNT) hybrid outperforms FLG by more than 2 orders of magnitude for thec-axis heat transfer, while its thermal resistance is 3 orders of magnitude lower than the state-of-the-art TIMs. When immersed in water, the G-CNT hybrid can provide sustainable cooling of high temperature and high heat flux hot surfaces via the solid-liquid interaction. Approaches to regulate the heat transfer across solid-liquid interface are also discussed.