摘要：SummaryIn recent years, nanoporous Si films have been intensively studied for their potential applications in thermoelectrics and the thermal management of devices. To minimize the thermal conductivity, ultrafine nanoporous patterns are required but the smallest structure size is largely limited by the spatial resolution of the employed nanofabrication techniques. Along this line, an effectively smaller characteristic length of a nanoporous film can be achieved with offset nanoslot patterns. Compared with periodic circular pores, the nanoslot pattern can achieve an even lower thermal conductivity, where a much smaller porosity is required using ultra-narrow nanoslots. The obtained low thermal conductivity can be understood from the thermally dead volume revealed by phonon Monte Carlo simulations. To further minimize the contribution from short-wavelength phonons, an additional 25% thermal conductivity reduction can be achieved with Ga ions implanted using a focused ion beam.Graphical abstractDisplay OmittedHighlights•Offset nanoslot patterns to minimize the in-plane thermal conductivity of thin films•Ion implantation to further reduce the thermal conductivity•Redistributed heat fluxes revealed by phonon Monte Carlo simulationsNanotechnology; Thermal engineering; Thermal property
