Lattice thermal conductivity of nanostructured thermoelectric materials based on PbTe

Abstract

We report the through-thickness lattice thermal conductivity Λl 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≤Tg≤620 K, and growth rates 1 μm h−1≤R≤4 μm h−1. All of our measurements approach Λl of bulk homogenous PbTe1−xSex alloys with the same average composition. For 5 nm≤h≤50 nm, Λl 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%; Λl is reduced by <25%.