The role of interface thermal boundary resistance in the overall thermal conductivity ofSi–Ge multilayered structures

Abstract

Nanoscale engineered materials with tailored thermal properties are desirable forapplications such as highly efficient thermoelectric, microelectronic and optoelectronicdevices. It has been shown earlier that by judiciously varying the interface thermalboundary resistance (TBR), thermal conductivity in nanostructures can be controlled. Inthe presented investigation, the role of TBR in controlling thermal conductivity at thenanoscale is analyzed by performing non-equilibrium molecular dynamics (NEMD)simulations to calculate thermal conductivity of a range of Si–Ge multilayered structureswith 1–3 periods, and with four different layer thicknesses. The analyses are performed atthree different temperatures (400, 600 and 800 K). As expected, the thermal conductivity ofall layered structures increases with the increase in the number of periods as well as withthe increase in the monolayer thickness. Invariably, we find that the TBR offered by theinterface nearest to the hot reservoir is the highest. This effect is in contrast to the usualnotion that each interface contributes equally to the heat transfer resistance in a layeredstructure. Findings also suggest that for high period structures the average TBR offered bythe interfaces is not equal. Findings are used to derive an analytical expression thatdescribes period-length-dependent thermal conductivity of multilayered structures.