Optical and Electronic Properties of SiTe_x(x=1,2) from First-Principles

Abstract

The optical and electronic properties of the α-SiTe, β-SiTe, and RX-SiTe_2 are investigated. A detailed analysis of electronic properties is done using standard density functional theory (DFT) and hybrid functional (HSE06) methods. The optical dielectric properties are studied under three different methods: standard DFT, many-body Green's functions (GW), and Bethe-Salpeter equation (BSE). Our calculations show that the SiTe compounds possess extremely high static dielectric constants in their bulk forms (ε_0({\bot}) = 68.58, ε_0({\parallel}) = 127.29 for α-SiTe, and ε_0({\bot}) = 76.23, ε_0({\parallel}) = 98.15 for β-SiTe). The frequency-dependent dielectric functions Im(ε) have very large values (>100) in the optical regime, which are among the highest of layered materials, suggesting them as excellent light absorbents in the corresponding frequencies. α-SiTe exhibits a high degree of optical anisotropy as compared to the other two compounds, consistent with their structural configurations. A strong interlayer excitonic effect is observed in bulk RX-SiTe_2. In addition, an analysis of Raman intensity is also performed.

References in corpus (4)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Excitonic Effects on the Optical Response of Graphene and Bilayer Graphene
• Optoelectronic Properties and Excitons in Hybridized Boron Nitride and Graphene Hexagonal Monolayers
• Strongly bound Mott-Wannier Excitons in GeS and GeSe monolayers