Tuning Lattice Thermal Conductance by Porosity Control in Ultrascaled Si and Ge Nanowires
Date of this Version2-22-2011
Applied Physics Letters 98, 083106 (2011)
Porous nanowires NWs with tunable thermal conductance are examined as a candidate for thermoelectric devices with high efficiency. Thermal conductance l of porous NWs is calculated using the phonon dispersion obtained from a modified valence force field model. Porosity in the NWs break the crystal symmetry leading to the reduction in ballistic l. 100 Si and Ge NWs show similar percentage reductions in l for the same amount of porosity. The model predicts an anisotropic reduction in l in SiNWs, with 111 showing the maximum reduction followed by 100 and 110 for a similar hole radius. The reduction in l is attributed to phonon localization and anisotropic mode reduction.
Electronic Devices and Semiconductor Manufacturing