Tuning thermal contact conductance at graphene-copper interface via surface nanoengineering.

Due to rapidly increasing power densities in nanoelectronics, efficient heat removal has become one of the most critical issues in thermal management and nanocircuit design. In this study, we report a surface nanoengineering design that can reduce the interfacial thermal resistance between graphene and copper substrate by 17%. Contrary to the conventional view that a rough surface tends to give higher thermal contact resistances, we find that by engraving the copper substrate with nanopillared patterns, an optimized hybrid structure can effectively facilitate the thermal transport across the graphene-copper interface. This counterintuitive behavior is due to the enhanced phonon interactions with the optimal nanopillared pattern. For pliable 2D materials like graphene, the structures can be easily bent to fit the surface formations of the substrate. The suspended areas of graphene are pulled towards the substrate via an attractive interatomic force, causing high local pressures (∼2.9 MPa) on the top region of nanopillars. The high local pressures can greatly enhance the thermal energy coupling between graphene and copper, thereby lowering the thermal contact resistances. Our study provides a practical way to manipulate the thermal contact resistance between graphene and copper for the improvement of nano-device performance through engineering optimal nanoscale contact.