Temperature-Driven Abrupt Changes in the Electronic Structure of 2D Si ₂ Te ₃ : A First-Principles Study

Si₂Te₃ has emerged as a promising two-dimensional material due to its compatibility with existing silicon-based semiconductor processes, its intrinsic p-type conductivity, which is rare among 2D materials, and its potential for diverse applications. Recently, experimental studies have suggested that Si₂Te₃ exhibits temperature-dependent changes in its optical and electrical properties. Although these observations are potentially linked to changes in Si-Si dimer orientations, the underlying mechanism remains unclear. Here, we employ first-principles density functional theory (DFT) calculations to investigate the impact of Si-Si dimer orientations on the electronic structure of Si₂Te₃. Our findings reveal that Si-Si dimer configurations can induce transitions between direct and indirect band gaps and significantly alter the hole effective mass. These results suggest a direct correlation between the orientations of Si-Si dimers and the resulting optical and electrical properties of Si₂Te₃, providing new insights into the fundamental properties of Si₂Te₃ and guiding future applications.