Cross-plane thermal conductivity temperature dependence for PbSnSe/PbSe thin film superlattice material from 100K to 300K

The temperature dependence of cross-plane lattice thermal conductivity for thin film IV-VI semiconductors grown by molecular beam epitaxy was measured. Samples consisting of PbSe/PbSrSe multiple quantum wells (MQWs) on PbSe/PbSnSe superlattices (SLs) were grown with variations in SL layer thickness and the number of SL pairs. Localized lattice temperatures within the MQW layers were extracted from analysis of continuous wave photoluminescence (PL) emission spectra at heat sink temperatures between 100 K and 250 K. These data, finite element analysis, and electrical characterization were used to determine cross-plane lattice thermal conductivity of two different SL materials. A SL material with three different PbSe/PbSnSe thicknesses (1.2/1.2, 1.8/1.8, and 2.4Z2.4 nm) exhibited a fairly constant lattice thermal conductivity from 1.2 to 1.3 WZmK as the sample was cooled from 250 K to 100 K. Another SL material with five different PbSe/PbSnSe thicknesses (0.5Z0.5, 1.0Z1.0, 1.6Z1.6, 2.1Z2.1, and 2.6Z2.6 nm) exhibited very low lattice thermal conductivities from 0.46 to 0.47 WZmK 250 K to 100 K. These results are consistent with reflection of low energy heat transporting acoustic phonons within the SL material.