Many-body perturbation-theory calculation of electronic and optical properties of β-phase Be₃N₂

Abstract The hexagonal β -phase of bulk Be 3 N 2 is a wide band gap semiconductor with potential ultraviolet (UV) optoelectronics applications. Here, we have performed the first theoretical study of the electronic and optical properties of the β phase of Be 3 N 2 considering many-body effects. In particular, we have obtained the electronic band structure and spectra of the dielectric function, complex refractive index and electron energy loss function. For the calculation of the band structure, both Density Functional Theory and G 0 W 0 approximation plus Wannier interpolation of the bands have been applied. For the calculation of the optical spectra, we have employed both the independent particle approach as well as the formalism that incorporates many-body and excitonic effects, by applying G 0 W 0 approximation and solving the Bethe-Salpeter equation (BSE). The results show, for instance, that the spectrum of the imaginary part of the dielectric function of β -Be 3 N 2 has an anisotropic behavior. Even more, the material shows its highest absorption peak in the UV range, which makes it interesting due to its possible high-temperature photodetection applications. Also, in the visible energy range of the spectrum, the index of refraction along the z -axis (see figure 1) is predicted to be around 1.6, which is a high value for a solid.