Tuning thermal conductance across sintered silicon interface by local nanostructures

•The first measurement of thermal boundary conductance across sintered interfaces.•Large controllability of Si–Si thermal conductance by local oxide nanostructures.•New route to reduce thermal conductivity of Si nanocomposite thermoelectrics.•Potential to make the thermal conductivity approach the amorphous limit.

A large reduction of heat conduction through silicon–silicon sintered interface by local oxide nanostructures is quantitatively demonstrated by a newly developed method to directly measure thermal boundary conductance across bonded interfaces. Together with the theoretical analysis that relates the thermal boundary conductance to thermal conductivity of densely-packed bulk nanocrystalline silicon, we identify a route to significantly reduce the thermal conductivity from the state-of-art value, even to approach the amorphous silicon value. The finding is useful for designing nanostructured bulk silicon thermoelectrics.

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