Strain engineering in optoelectronic properties of MoSi<sub>2</sub>N<sub>4</sub> monolayer: ultrahigh tunability
Hosein Alavi-Rad
Abstract
Abstract Controllable optical properties are important for optoelectronic applications. Recently, the two-dimensional MoSi 2 N 4 monolayer was successfully synthesized by chemical vapor deposition, showing remarkable stability in the ambient condition. Motivated by this achievement, herein, we investigate the electronic and optical properties of MoSi 2 N 4 monolayer under mechanical strain through the first-principle calculations. The considered monolayer is structurally and dynamically stable. It is a semiconductor with an indirect band gap of 1.92 eV so that the size of the band gap is easily tuned under biaxial strain. By increasing the tensile strain up to 6%, the effective mass of holes increases to 3.84 m e whereas the effective mass of electrons reduces to 0.43 m e . In other words, under the strain of 6%, one can have strongly localized holes together with free electrons simultaneously in MoSi 2 N 4 monolayer, which could bring fascinating features like ferromagnetism and superconductivity. Under the strain from 10% to 18%, a Mexican hat dispersion is observed in the highest valence band in such a manner that its coefficient increases from 0.28 to 2.89 eVÅ, indicating the potential thermoelectric application of MoSi 2 N 4 monolayer under strain. Under the strain of 8%, the light absorption coefficient is improved by almost 70%. More importantly, this monolayer tolerates biaxial strain up to 18% and stays mechanically and dynamically stable, making it very promising for flexible nanoelectronics. The controllable electronic and optical properties of MoSi 2 N 4 monolayer may open up an important path for exploring next-generation optoelectronic applications.