Structural, Optical, and Electronic Properties Analysis of Praseodymium Doped ZnO: Insights from Density Functional Theory with GGA+U Approach

Abstract

ZnO is widely used as a semiconductor material due
to its wide bandgap, high exciton binding energy, and excellent
transparency in the visible range, which make it suitable for
optoelectronic applications. Doping in ZnO is important because
it allows for controlling its electrical properties, enables the
tuning of conductivity, and enhances its functionality for specific
applications. Doping can introduce new energy levels within the
bandgap. Moreover, it improves the performance of ZnO-based
devices. This study explored the structural, optical, and
electronic properties of pure and Praseodymium ion (Pr3+) doped
ZnO using GGA+U based DFT. Results agreed with prior
research, showing compatible lattice parameters and band gap
for pure ZnO. Increasing Pr concentration expanded lattice
parameters and volumes while reducing the energy band gap. Pr
doping shifted the Fermi level to the upper conduction band,
causing an overlap between the conduction and valence bands.
This indicated a transition from a semiconductor to an n-type
degenerate semiconductor with metal-like characteristics. Higher
doping concentrations led to a shift in density of states towards
lower energies. Computed optical properties exhibited red shifts
in absorption peaks and increased absorption in the near and far
ultraviolet regions following Pr doping. Similar red shifts were
observed in the reflectivity spectrum and other optical
properties. The real dielectric constant (ε1 (ω)) displayed negative
values, signifying metallic behavior at specific photon energies,
consistent with band structure optimization.