The guide and focus of heat flow in nanoporous silicon membrane at room temperature: A molecular dynamics study

Ray-like heat manipulation using an arrangement of pores at the nanoscale has emerged as an innovative way for electronic devices, but the atomistic insights are yet unclear. Here, we investigate the effect of structural parameters and temperature on heat guiding and focusing in nanoporous Si phononic crystalline (PnC) membrane by performing molecular dynamics simulations at room temperature. In samples with parallel arrangements of pores with diameters of a few nanometers, phonon backscattering is found to always occur with sinusoidal temperature distribution, and better guiding of heat flow is obtained for larger necks. Using the radial arrangement of pores, focusing of heat flow is realized, and moreover, the focusing degree is enhanced for a narrower neck and lower temperature. This work paves a way to use a convergent thermal lens for thermal activation and a divergent lens for protecting the temperature-sensitive components.