Effect of nanodot areal density and period on thermal conductivity in SiGeSi nanodot superlattices

We report on the effect of nanodot (ND) areal density and period on cross-plane thermal conductivity κ⊥ in SiGeSi nanodot superlattices (NDSLs). For all ND areal densities considered, we found that κ⊥ in SiGeSi NDSLs decreased monotonically with decreasing period and reached values lower than those in typical SiGe alloys (∼6.5 W m-1 K-1). At short periods, κ⊥ 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 κ⊥. This work indicates that low κ⊥ can be attained in SiGeSi NDSLs either with a low SL period, a high ND areal density, or both.