The strain engineering is an important approaches to modulate the electronic and optical properties of materials. Recently, a new two dimensional material monolayer MoSi₂N₄ has been successfully synthesized with excellent electronic performance. The electronic properties of monolayer MoSi₂N₄ without and with in-plane strain are systematically investigated by first-principles calculation. The calculation results reveal monolayer MoSi₂N₄ is an indirect bandgap semiconductor with bandgap 1.74 eV (PBE) and 2.31 eV (HSE06), but it can be transformed to a direct bandgap under the certain in-plane strain, such as 3% and 4% biaxial compressive strain. In-plane strain can effectively modulate the band structure, bandgap, and the carrier effective mass. Furthermore, the optical properties of unstrained and transformed to direct bandgap situations are calculated. The light absorption capacity of monolayer MoSi₂N₄ is stronger in the ultraviolet band, and can be changed when it is transformed to a direct bandgap. The electrical and optical properties can be modulated by strain engineering, making it is a promising candidate of strain-modulated optoelectronic devices.

应变工程是调节材料电子和光学性质的重要方法。最近，一种新型二维材料单层MoSi ₂ N ₄已成功合成，具有优异的电子性能。通过第一性原理计算系统地研究了单层MoSi ₂ N ₄没有和有面内应变的电子特性。计算结果表明单层MoSi ₂ N ₄是一种带隙为1.74 eV（PBE）和2.31 eV（HSE06）的间接带隙半导体，但在一定的面内应变下，如3%和4%的双轴压缩应变下，它可以转化为直接带隙半导体。面内应变可以有效地调节能带结构、带隙和载流子有效质量。此外，还计算了无应变和转换为直接带隙情况的光学特性。单层MoSi ₂ N ₄的光吸收能力在紫外波段较强，可转变为直接带隙。电学和光学特性可以通过应变工程进行调制，使其成为应变调制光电器件的有希望的候选者。