Tuning of thermal conductivity in Si-membranes with nanoholes

AGUSTIN MANCARDO VIOTTI; M. FLORENCIA CARUSELA; ALEJANDRO MONASTRA; EDGAR ALEJANDRO BEA

Los Polvorines

Workshop; First Workshop at UNGS on Transport Phenomena and Non-Equilibrium Processes; 2018

Universidad Nacional de General Sarmiento

For nonmetallic materials, heat flow is mainly transport of phonons. As nanostructures have sizes comparable to phonon coherence length, thermal transport is mainly in a semiballistic regime. Conductivity can be tuned by border effects or superimposed structures where scattering processestake place. Silicon membranes are typical examples, where thermal conduction can be controled by the engineering of structures or patterns on them. We study numerically the thermal conductivity in a suspended Si-membranes. We compare the case of flat uniform membranes with nanostructured periodic holes, in the presence of thermal gradients around room temperature. Both membrane thickness and holes are of the order of 10 nm. We found that thermal conductivity depends on the number of holes and its separation. The simulations are based on molecular dynamics. The problem is approached by two Si interaction models, empirical and semi-empirical, which allow studies at different system size scales, considering some level of semiempirical quantum detail in order to analyze some eventual electronic contribution in the energy transport. As a complementary part of the work concerning the simulations, we also describe the thermalization process, usually not fully discussed for theoperating conditions of these type of nanostructures.