Stability, electronic and mechanical properties of chalcogen (Se and Te) monolayers

Abstract

The successful experimental fabrication of 2D tellurium (Te) has resulted in growing interest in the monolayers of group VI elements. By employing density functional theory, we have explored the stability and electronic and mechanical properties of 1T-MoS₂-like chalcogen (α-Se and α-Te) monolayers. Phonon spectra are free from imaginary modes suggesting these monolayers to be dynamically stable. The stability of these monolayers is further confirmed by room temperature AIMD simulations. Both α-Se and α-Te are indirect gap semiconductors with a band gap (calculated using the hybrid HSE06 functional) of 1.16 eV and 1.11 eV, respectively, and these gaps are further tunable with mechanical strains. Both monolayers possess strong absorption spectra in the visible region. The ideal strengths of these monolayers are comparable with those of many existing 2D materials. Significantly, these monolayers possess ultrahigh carrier mobilities of the order of 10³ cm² V⁻¹ s⁻¹. Combining the semiconducting nature, visible light absorption and superior carrier mobilities, these monolayers can be promising candidates for the superior performance of next-generation nanoscale devices.