Effect of nanodot areal density and period on thermal conductivity in SiGe/Si nanodot superlattices

We report on the effect of nanodot (ND) areal density and period on cross-plane thermal conductivity kappa(perpendicular to) in SiGe/Si nanodot superlattices (NDSLs). For all ND areal densities considered, we found that kappa(perpendicular to) in SiGe/Si NDSLs decreased monotonically with decreasing period and reached values lower than those in typical SiGe alloys (similar to 6.5 W m(-1) K(-1)). At short periods, kappa(perpendicular to) was as low as 2.0-2.7 W m(-1) K(-1) and at a fixed period, increasing the ND areal density led to lower kappa(perpendicular to). This work indicates that low kappa(perpendicular to) can be attained in SiGe/Si NDSLs either with a low SL period, a high ND areal density, or both. (c) 2008 American Institute of Physics.