Single-layer Ag6S2: First principles investigation of a new two-dimensional direct bandgap semiconductor

In this study, using first-principles density functional theory, a new two-dimensional semiconductor Ag6S2 is predicted. Phonon calculations and molecular dynamic simulations confirm that this new monolayer structure can be stable at the room temperature. Investigation on the electronic band structure calculations show that Ag6S2 monolayer has a direct bandgap of 2.64 eV at the Gamma high symmetry point. External tensile strain can alter the bandgap value and a direct-indirect transition occurs for a strain value larger than epsilon = 4%. Our theoretical analysis indicates that silicene can be a suitable substrate material for Ag6S2 with good lattice matching. We believe that when synthesized, the Ag6S2 monolayer should be a good candidate for new design electronics, semiconductors and optoelectronic devices.