Compositionally segmented thermoelectric BiSbTe thin films on Cr/Si(100)

Compositionally segmented thermoelectric (CS-TE) structures improve thermal energy conversion efficiency across large thermal gradients. However, their increased design complexity complicates performance modeling and optimization. In this study, we fabricate CS-TE BiSbTe thin films on Cr-buffered Si(100) substrates. By adopting a multidisciplinary approach, we aim to broaden the technological applicability and strategic relevance of advanced TE systems. We systematically analyze the influence of deposition pressures (5, 7, and 10 mTorr) on TE performance. Variations in working pressure alter the Bi/Sb atomic ratio in the films, while the Te content remains stable. This enables the controlled formation of CS structures. At 323 K, the power factor (PF) of TE thin films reaches 0.7, 2.4, and 7.3 mW/mK2 under 5, 7, and 10 mTorr deposition conditions, respectively. The Cr-buffered layer significantly improves the electrical conductivity of CS-TE BiSbTe films. We further engineer a p-type single-leg device integrating nanostructured Bi0.35Sb1.65Te3, Bi0.37Sb1.63Te3, and Bi0.4Sb1.60Te3 layers. These materials are optimized to achieve peak TE PF values across a wide temperature range (320 to 500 K) while ensuring robust interfacial adhesion. The CS-TE device generates 3 mW/cm2, showing a 15% improvement over single-composition samples at a 100 K temperature difference.