Mechanism of Bonding and Defect Evolution of Deformed SbTe Semiconductors under Temperature Effects.

Recently, the enhanced plasticity of SbTe-based thermoelectric (TE) semiconductors has been expected to promote the device application of precise temperature control and refrigeration. Although it should be attributed to van der Waals (VdW) bonds in the sublattice, which are weak and sensitive to external stimuli such as force and temperature, the evolution mechanism has not yet been fully explored. Moreover, temperature is crucial during the processing and application of TE devices, significantly influencing lattice deformation and structural failure. Therefore, it is necessary to understand the behaviors of bonds and lattice defects in deformed SbTe under temperature effects. In this study, we simulated the shear deformation of SbTe at 200 K-500 K using the molecular dynamics method. The results demonstrate that plasticity highly depends on dynamic VdW bonding and defect evolution. At 200 K, the SbTe lattice primarily coordinates deformation and dissipates strain energy via ordered reforming of VdW bonds and related dislocation slippage, which may be hindered by thermally induced disorder at higher temperatures, leading to a tripling of fracture strain compared to the distorted structure at 500 K. This work offers a physical insight into the response of ductile inorganic semiconductors to thermo-mechanical coupling, which is helpful for designing advanced TE devices.