Lattice thermal conductivity of nanostructured thermoelectric materials based on PbTe

We report the through-thickness lattice thermal conductivity Lambda(l) of (PbTe)(1-x)/(PbSe)(x) nanodot superlattices (NDSLs) over a wide range of periods 5 nm <= h <= 50 nm, compositions 0.15 <= x <= 0.25, growth temperatures 550 K <= T(g)<= 620 K, and growth rates 1 mu m h(-1)<= R <= 4 mu m h(-1). All of our measurements approach Lambda(l) of bulk homogenous PbTe(1-x)Se(x) alloys with the same average composition. For 5 nm <= h <= 50 nm, Lambda(l) is independent of h; a result we attribute to short mean-free paths of phonons in PbTe and small acoustic impedance mismatch between PbTe/PbSe. We alloyed the PbTe layers of four NDSLs with SnTe up to a mole fraction y=18%; Lambda(l) is reduced by < 25%.