Ab Initio Investigations of Optoelectronic and Transport Behavior of Mn and Eu-Doped Zn_xA_xSiGeN₄ Using GGA plus U Functional: A Study for Optoelectronic Devices

This article examines the optoelectronic and transport properties of Zn(x)A(x)SiGeN(4) (A = Mn, Eu) through a comprehensive study. The study utilizes first-principles density functional theory (DFT) calculations with the Wien2k code. The optimized structural parameters, including the tolerance factor, critical radius, and formation energy, were initially determined. The energy band structure, densities of electronic states, and energy dependence of the optical functions were determined. The observed phenomenon exhibits a reduction in the energy difference between the valence and conduction bands for the materials under investigation. Precisely, the band gaps were measured to 4.1 eV, 2.0 eV (up)/2.8 eV (dn), and 0.8 eV (up)/2.4 eV (dn), respectively, for the respective doping of Eu and Mn. It has been determined that the material exhibits a direct band gap with a transition occurring along the Gamma-Gamma symmetry point. The electronic interband changes responsible for the observed optical spectra were identified. The thermoelectric parameters, such as the Seebeck coefficient, electrical and thermal conductivities, and figure of merit, were calculated using the standard Boltzmann transport theory in parallel. Based on our findings, it has been determined that the compounds under investigation exhibit promising characteristics that make them viable contenders for utilization in thermoelectric applications. The process of doped compounds Zn0.95Eu0.05SiGeN4 and of Zn0.95Mn0.05SiGeN4 has the potential to alter the characteristics of the material significantly, suggesting being promising for utilization in emerging fields such as advanced electronics and photovoltaic.