Strain engineering in optoelectronic properties of MoSi₂N₄ monolayer: ultrahigh tunability

Abstract

Controllable optical properties are important for optoelectronic applications. Recently, the two-dimensional MoSi2N4 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 MoSi2N4 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 me whereas the effective mass of electrons reduces to 0.43 me. In other words, under the strain of 6%, one can have strongly localized holes together with free electrons simultaneously in MoSi2N4 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 MoSi2N4 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 MoSi2N4 monolayer may open up an important path for exploring next-generation optoelectronic applications.

Emerging Versatile Two‐Dimensional MoSi2N4 Family

“…When the inner N atom is replaced by C, MoSi 2 CN 3 , and WSi The electronic transition of monolayer MA 2 Z 4 from semi conductor to metal can be triggered by applying inplane strains. [63,109] The bandgap of monolayer MoSi 2 N 4 decreases with the increasing inplane biaxial strain (Figure 9a). The relation between bandgap (E g ) and strain (e) is fitted as [109] E g = 0.004 e 2 − 0.17 e + 1.87.…”

“…[63,109] The bandgap of monolayer MoSi 2 N 4 decreases with the increasing inplane biaxial strain (Figure 9a). The relation between bandgap (E g ) and strain (e) is fitted as [109] E g = 0.004 e 2 − 0.17 e + 1.87. Under an inplane biaxial strain of 4% (6%), the effective mass of holes is -2.33 m e (-3.84 m e ) and the effective mass of electrons is 0.48 m e (0.43 m e ).…”

“…b) Out-of-plane strain effect on bilayer MoSi 2 N 4 . Reproduced with permission [109,111]. Copyright 2021, MDPI, Copyright 2021, APS.…”

Tunable type-II lateral MoSi2N4/WSi2N4 heterostructures for photocatalytic applications

“…8 Suitable strains have been identified to trigger intriguing influences on the MoSi 2 N 4 monolayer and its van der Waals heterostructures. [51][52][53][54] Thus, we wonder if the strains will affect the type-II band alignment and direct-band nature in the (MoSi 2 N 4 ) 8 (WSi 2 N 4 ) 8 lateral heterostructure. Fig.…”

First-Principles Investigation of MXene/MoSi2N4 van der Waals Heterostructures: Strong Fermi Level Pinning Effect Resulting in Ohmic Contact with Low Contact Resistance

“…This unique property makes it completely different from traditional semiconductors such as MoS 2 and suggests that MoSi 2 N 4 has great potential as a channel material for FET. Therefore, exploring suitable electrode materials and investigating the internal mechanism in 2D semiconductor devices, using MoSi 2 N 4 as a starting point, could help advance the development of electronic devices and unlock the full potential of this unique material …”