The Impact of Interface Defects on Thermal Boundary Resistance at a Si|C Interface

Due to the increasing complexity and miniaturization of microelectronics, material interfaces are now the dominant source of thermal resistance in many integrated circuits and electronic devices. While the literature on thermal boundary resistance is extensive, the theory remains poorly understood. This is particularly true for the case of defects at the interface. Data and results on three defects at a Si|C interface are presented—an interstitial N pair and two different substitutional Ge's. It is found that the interstitial N pair, as well as one of the Ge defects, reduces thermal boundary conductivity considerably whereas the substitutional Ge placed directly at the interface is largely transparent. For the first time, it is shown that a defect (substitutional Ge, red) is effectively transparent to heat flow across a material interface. The interface occurs at the junction of Si (cyan) and C (green) inside a nanowire. An interstitial NiNi is also studied, and as expected, increases Kapitza resistance associated with the defect.