First-Principles Investigation of the Structural, Electronic, and Optical Properties of Tl1-xBxN Alloys in the Zinc-Blende Phase

Abstract

In this work, a comprehensive first-principles investigation of the structural, electronic, and optical properties of Tl₁₋ₓBₓN (x = 0.25, 0.50, and 0.75) alloys crystallizing in the zinc-blende phase is presented. To the best of our knowledge, a systematic theoretical study of these ternary alloys combining structural optimization, electronic structure analysis, and optical response including spin–orbit coupling effects has not been reported previously. The calculations were performed within density functional theory using the generalized gradient approximation. The optimized lattice parameters were obtained from total energy–volume calculations and exhibit a composition-dependent trend consistent with Vegard’s law, confirming the structural stability of the considered alloys. The electronic band structures reveal a pronounced dependence of the band gap on boron concentration, demonstrating the possibility of band gap engineering through composition tuning. The inclusion of spin–orbit coupling leads to a noticeable modification of the electronic structure and a reduction in the band gap, reflecting the significant relativistic effects associated with thallium atoms. The optical properties were analyzed in the photon energy range of 0 - 14 eV. The calculated dielectric function, absorption coefficient, refractive index, and reflectivity show strong sensitivity to boron content, indicating tunable optical behavior. Overall, the results highlight the potential of Tl₁₋ₓBₓN alloys for advanced optoelectronic and photonic applications, particularly in tunable semiconductor and ultraviolet device technologies.