In this work, detailed investigations of the electronic and optical properties of a Janus Ga₂STe monolayer under a biaxial strain and electric field have been performed using density functional theory. Via the phonon spectrum and ab-initio molecular dynamics simulations, the dynamical and thermal stabilities of the Janus Ga₂STe monolayer are verified. Our obtained results showed that the Janus Ga₂STe exhibits a direct semiconducting characteristic and its band gap depends greatly on the biaxial strain. While both the electronic and optical properties are very weakly dependent on the electric field, strain engineering can cause a direct–indirect band gap transitions in the Janus Ga₂STe. At equilibrium, the optical absorbance of the Janus Ga₂STe monolayer is activated in the infrared light region of about 0.9 eV, which is close to its band gap value. The main peak of the optical absorbance spectrum is located in the ultraviolet light region with an absorbance intensity of 11.914 × 10⁴ cm⁻¹ may be increased by compression strain. In particular, the absorbance intensity of the Janus Ga₂STe monolayer increases rapidly in the visible light region, reaching 4.810 × 10⁴ cm⁻¹ and can be altered by strain. Our results not only show that the Janus Ga₂STe monolayer has many promising applications in opto-electronic devices but also motivates experimental works on Janus structures in near future.

在这项工作中，已经使用密度泛函理论对Janus Ga ₂ STe单层在双轴应变和电场下的电子和光学性质进行了详细的研究。通过声子谱和从头算分子动力学模拟，验证了Janus Ga ₂ STe单层的动力学和热稳定性。我们获得的结果表明，Janus Ga ₂ STe具有直接的半导体特性，其带隙在很大程度上取决于双轴应变。尽管电子和光学特性都非常弱地依赖于电场，但是应变工程可以在Janus Ga _2中引起直接-间接带隙跃迁STe。在平衡状态下，Janus Ga ₂ STe单层的吸光度在约0.9 eV的红外光区域被激活，该区域接近其带隙值。光吸收光谱的主峰位于紫外光区域，其吸收强度为11.914×10 ⁴  cm ^-1可以通过压缩应变而增加。特别地，Janus Ga ₂ STe单层的吸收强度在可见光区域迅速增加，达到4.810×10 ⁴  cm ^-1，并且可以通过应变来改变。我们的结果不仅表明Janus Ga ₂STe单层膜在光电器件中有许多有希望的应用，但在不久的将来也会激发对Janus结构的实验工作。