Structural, electronic, thermoelectric and optical properties of 2D hexagonal beryllium telluride under DFT investigation

Abstract

In this study we have investigated structural, electronic, thermoelectric and optical properties of monolayer beryllium telluride compound in the hexagonal lattice phase (h-BeTe) using first principle calculations under density functional theory (DFT) approach. Using the frequency dependent phonon dispersion curves, we have analyzed the stability of the h-BeTe compound. The investigation of structural properties, including density of states (DOS) and band structure, demonstrates that h-BeTe is a direct bandgap semiconductor material with bandgap value of 3.054 eV. The h-BeTe compound exhibits exceptional thermoelectric behavior for a temperature range of 50–800 K, as confirmed by the calculated thermoelectric parameters, including thermal conductivity, electrical conductivity, Seebeck coefficient and figure of merit (ZT). It is vital that h-BeTe exhibits exceptional thermoelectric properties specifically, the figure of merit (ZT > 0.9) provides the efficiency of h-BeTe compound in temperature range of 300–800 K. The optical properties of h-BeTe are investigated for the first time with its interaction in applied external electric field based on various optical parameters such as real and imaginary dielectric constant, refractive index n(ω), extinction coefficient k(ω), absorption coefficient α(ω) and reflectivity R(ω). The optical properties analysis reveals the monolayer hexagonal beryllium telluride to be mostly active in the visible-UV spectrum. These findings have the potential to foster researchers to explore h-BeTe compound experimentally for possible optoelectronic applications.