Design of ZnO with Reduced Direct Bandgap using First-principles Calculation: Electronic, Band Structure, and Optical Properties

In the current work, lattice parameters, band structure, and optical characteristics of neat and doped ZnO are studied by utilizing ultrasoft pseudopotentials (USP) and generalized gradient approximation (GGA) with the support of Firstprinciples calculation (FPC) derived from density functional theory (DFT). The measurements had been performed in the supercell geometry that had been optimized. To discover the lattice parameters, electronic band structure, and optical characteristics of V-doped ZnO, the FPC based on DFT has been applied in CASTEP. The calculated lattice parameters are agree with observed experimental data. The volume of the doped system grows as the content of Vdoping in it increases. Pure and doped ZnO were investigated for band structure and energy bandgaps using the Monkhorst-Pack scheme’s k-point sampling techniques in the high symmetry direction of the Brillouin zone (G-A-H-K-G-M-L-H). In the presence of high V content, the bandgap energy decreases from 3.331 to 2.055 eV. From the band E-K diagram (V.B and C.B), PDOS and DOS diagrams insight into the electronic structure of the atom and the amount to which each energy band contributes to a specific atomic orbital were specified. The bandgaps were manipulated so that they narrowed, resulting in a redshift of the absorption spectrum in the IR region. The imaginary and real parts of the extinction coefficient, refractive index, and dielectric function have all increased at lower photon energies.