Ultra‐Efficient Heat Transport Across a “2.5D” All‐Carbon sp²/sp³ Hybrid Interface

Abstract Single‐ and few‐layer graphene‐based thermal interface materials (TIMs) with extraordinary high‐temperature resistance and ultra‐high thermal conductivity are very essential to develop the next‐generation integrated circuits. However, the function of the as‐prepared graphene‐based TIMs would undergo severe degradation when being transferred to chips, as the interface between the TIMs and chips possesses a very small interfacial thermal conductance. Here, a “2.5D” all‐carbon interface containing rich covalent bonding, namely a sp 2 /sp 3 hybrid interfaces is designed and realized by a plasma‐assisted chemical vapor deposition with a function of ultra‐rapid quenching. The interfacial thermal conductance of the 2.5D interface is excitingly very high, up to 110–117 MWm −2 K −1 at graphene thickness of 12–25 nm, which is even more than 30 % higher than various metal/diamond contacts, and orders of magnitude higher than the existing all‐carbon contacts. Atomic‐level simulation confirm the key role of the efficient heat conduction via covalent C−C bonds, and reveal that the covalent‐based heat transport could contribute 85 % to the total interfacial conduction at a hybridization degree of 22 at %. This study provides an efficient strategy to design and construct 2.5D all‐carbon interfaces, which can be used to develop high performance all‐carbon devices and circuits.