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

TL;DR

This study uses first-principles calculations to explore the optical and electronic properties of SiTe compounds, revealing their high dielectric constants, optical anisotropy, and strong excitonic effects, indicating potential for optoelectronic applications.

Contribution

It provides a comprehensive first-principles analysis of SiTe_x compounds' optical and electronic properties, highlighting their exceptional dielectric and excitonic characteristics.

Findings

High static dielectric constants in SiTe compounds

Large frequency-dependent dielectric values in the optical regime

Strong interlayer excitonic effects in RX-SiTe_2

Abstract

The optical and electronic properties of the {\alpha}-SiTe, {\beta}-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 ({\epsilon}_0({\bot}) = 68.58, {\epsilon}_0({\parallel}) = 127.29 for {\alpha}-SiTe, and {\epsilon}_0({\bot}) = 76.23, {\epsilon}_0({\parallel}) = 98.15 for {\beta}-SiTe). The frequency-dependent dielectric functions Im({\epsilon}) 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. {\alpha}-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.