Compressive strain engineering in inclined SnSb2Te4 thin film for high-performance TTE photodetection

Abstract

Self-powered photodetectors based on the transverse thermoelectric (TTE) effect have attracted significant attentions due to their ultrasensitive detection and sub-100-ns-level response speeds. However, achieving practically viable detection sensitivity remains a critical challenge in this emerging field. Here, we propose a substrate-induced-compressive strain strategy to enhance the TTE performance in c-axis inclined SnSb₂Te₄ thin films. Through systematic investigation of the films deposited on three lattice-mismatched substrates (MgO, SrTiO₃, and LaAlO₃), the controlled strains enhance electrical conductivity, suppress thermal conductivity, and amplify Seebeck coefficient anisotropy. This synergistic optimization enables superior TTE detection performance under 308 nm UV pulsed laser irradiation, whose high sensitivity is 20.5 V/mJ, fast response time is 73 ns and excellent figure of merit is 566 mV/ns. Our findings not only position SnSb₂Te₄ as a promising candidate for weak-signal UV photodetection but also establish substrate-induced-compressive strain as an effective strategy for developing high-sensitivity and fast-response TTE photodetectors.