Crystal and electronic structure of a quasi-two-dimensional semiconductor Mg₃Si₂Te₆

We report the synthesis and characterization of a Si-based ternary semiconductor Mg₃Si₂Te₆, which exhibits a quasi-two-dimensional structure, where the trigonal Mg₂Si₂Te₆ layers are separated by Mg ions. Ultraviolet-visible absorption spectroscopy and density functional theory calculations were performed to investigate the electronic structure. The experimentally determined direct band gap is 1.39 eV, consistent with the value of the density function theory calculations. Our results reveal that Mg₃Si₂Te₆ is a direct gap semiconductor, which is a potential candidate for near-infrared optoelectronic devices.