Cross-plane thermal conductivity of a PbSnSe/PbSe superlattice material

Abstract

The cross-plane thermal conductivity of a PbSnSe/PbSe multi-period superlattice (SL) grown by molecular beam epitaxy is obtained from continuous wave photoluminescence (PL) measurements and finite element analysis (FEA). PL measurement and FEA for a structure consisting of a multiple quantum well light emitting layer on top of a PbSnSe/PbSe SL with three different periodicities of 2.4, 3.6, and 4.8 nm revealed a cross-plane lattice thermal conductivity of 0.8 W/mK. The 58% reduction relative to the 1.9 W/mK value for bulk PbSe is attributed to enhanced scattering and/or reflection of acoustic phonons within the short-period SL material.

Lattice thermal conduction in ultra-thin nanocomposites

“…18 In particular, the work by Jeffers et al 18 echoes our prediction that the significant reduction in the cross-plane thermal conductivity of SLs of periods shorter than 5 nm is the result of stronger scattering of phonons by interfaces. To the best of our knowledge, there are no reports of the FIG.…”

“…4,8,13,17 In particular, Slack 17 has suggested that materials prepared using techniques which produce glass-like hugely reduced lattice thermal conductivity j ph without significantly reducing the power factor PF ¼ S 2 r, should help enhance ZT. Experimental studies 10,18 have clearly indicated the role of strong interface scattering of phonons in generating large reduction in j ph for thin-period superlattice (SL) structures. However, no fullscale and accurate calculations of phonon scattering rates and conductivity for nanocomposites of different dimensionalities and different volume fractions have been carried out that assess the full extent of the role of phonons in the enhancement of ZT with a high degree of confidence.…”

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

“…For example, sample M212 at a heat sink temperature of 150 K and 2.6 W of absorbed power has a MQW lattice temperature of 184.6 K. Hot spot MQW lattice temperatures were then used as boundary conditions in finite element modeling (QuickField) to determine the total thermal conductivity of the SL material. As with prior work [11], a sample with binary PbSe (M141) having known total thermal conductivity of 4.8 W/mK at 150 K, extrapolated from the data of Shalyt et al [13], was used to fit the Gaussian shaped pump laser spot size. A good fit was obtained with a beam spot FWHM of 530 μm, which agrees well with knife-edge measurements.…”

“…Figure 1 summarizes the three samples where the thicknesses of layers within each sample are calculated from total measured IV-VI layer thickness and shutter open times, which were as short as 3.6 sec, during MBE growth. PL measurements and cross-plane lattice thermal conductivity determination were performed according to procedures described previously [11]. Instead of maintaining the copper heat sink temperature with a thermoelectric cooling module, as done earlier, we used a liquid nitrogen cryostat with infrared transparent windows for diode laser (875 nm InGaAs diode pump laser) illumination and mid-IR PL light collection.…”

Ab initio description of the thermoelectric properties of heterostructures in the diffusive limit of transport

“…Made available by state‐of‐the art heteroepitaxy , SL consist of alternating thin layers of different materials stacked periodically. Most prominent applications of TE SL are , Si/Ge and SL based on PbTe and PbSe . Other SL based on Bi/Sb () or skutterudites () showed negligible or only small enhancements of the TE efficiency.…”