Tunable properties of the stable SiSeS Janus monolayer under biaxial strain: First-principles prediction

The electronic structure, optical and thermoelectric properties of Janus T-phase SiSeS monolayer under biaxial strain have been analyzed using the first-principles calculations. Our calculations identified the Janus T-phase SiSeS monolayer as an indirect semiconductor with an energy band gap of 0.77 eV at the equilibrium state, which can be tuned effectively through a biaxial strain. The band gap tends to decrease slowly when the large compression biaxial strains are applied. It is of interest that a semiconductor-metal phase transition was obtained under biaxial compression strain of − 8%. Moreover, the optical properties rise under biaxial strain with an enhanced absorption coefficient in the infrared region. Interestingly, the compressive biaxial strain combined with p-type doping in the Janus T-phase SiSeS monolayer produced a large electronic figure of merit (ZTe) of 7.0 at 300 K. The predicted results show the potential applications of Janus T-phase SiSeS monolayer for optoelectronic and thermoelectric devices.