Optoelectronic properties of Nd3+ doped CaTa2O6: Insights from the GGA + U calculations

The current work is a study of optoelectronic properties of Nd3+ doped CaTa2O6 using the FP-LAPW (full potential-linear augmented plane wave) method as implemented within the WIEN-2k code. The GGA (generalized gradient approximation) has been used as EXC (exchange-correlation) functional for the calculations of electronic and optical properties with Hubbard correction. The optimized crystal structure shows close agreement with experimental results. In order to ensure the accuracy of the electronic band structure and optoelectronic properties, we have used the effective Hubbard parameter “U” for the 4f-electrons of the Nd atom. Electronic band structure study shows the semiconducting nature with a direct band gap. The VBM (valance band maximum) and CBM (conduction band minimum) are located at the Γ-point of the Brillouin zone. Optical properties were studied by taking into account the interband transitions. A number of optical transition levels have been found. We have evaluated various optical constants, like the absorption coefficient, reflectivity, energy loss function and refractive index as function of incident photon energy. Both band structure and optical parameters have been investigated for up and down electron spin configurations. Nd3+ doped CaTa2O6 possesses high degree of spin symmetry, except at low energy, and absorbs ultraviolet photons strongly and weakly reflects photons in the infrared and visible energies. These optical characteristics can be useful for optoelectronic device applications.