Investigating the Effects of Biaxial Strain on the Electronic, Optical and Thermoelectric Properties of the Puckered Si<sub>2</sub>SeTe Monolayer

Abstract

In this paper, we have investigated the electronic, optical and thermoelectric properties of the puckered Si2SeTe monolayer when subjected to various levels of biaxial strain ranging from −10% to +10%. The structural stability, as determined by the cohesive energy, shows that the puckered Si2SeTe structure is energetically stable. The results reveal that the unstrained Si2SeTe monolayer is an indirect band gap semiconductor with an energy gap of 0.5 eV, which can be effectively adjusted with biaxial strain. The semiconductor–metal phase transition occurs when the monolayer is compressed by −4% biaxial strain. Moreover, the optical properties, including the real ε1(ω) and imaginary ε2(ω) components of the dielectric function, extinction coefficient K(ω), reflectivity R(ω), refractive index n (ω), and absorption coefficient α (ω), were evaluated as a function of the energy of light and under biaxial strain. We discovered that the puckered Si2SeTe monolayer is capable of absorbing light in the visible region of 64.7×104 cm−1, 73.8×104 cm−1 for equilibrium state and under the compression strain (−8%), respectively. Lastly, the influence of biaxial strain on thermoelectric properties such as electrical conductivity (σ/τ), electronic thermal conductivity (ke/τ), Seebeck coefficients, and electronic figure of merit (ZTe) was studied. The calculated electronic figure of merit ZTe presents an improvement in the p-type doping (μ<0) under the tensile biaxial strain. Taking into account the optical and thermoelectric properties, the puckered Si2SeTe monolayer is a promising material for use in optoelectronic devices and energy conversion technologies.