Influence of Hubbard U on the Structural and Electronic Properties of Pure and La-Doped ZnO

Abstract

The lattice parameters, average bond length, band structure and density of states (DOS) of pure ZnO and La-doped ZnO were calculated using the density functional theory (DFT) with the addition of Hubbard U (DFT+U) correction method. Lanthanum, La is a p-type dopant that might be viewed as a practical method for improving a piezoelectric nanogenerator's performance. The calculated lattice parameters and volume of pure ZnO expanded after La doping which are a=b=3.251 Å, c=5.208 Å and V= 48.346 Å3. The Zn-O bond length of La-doped ZnO is higher than that of pure ZnO which makes the La-doped ZnO having stronger bonding than pure ZnO. The calculated band gap of pure ZnO was 3.415 eV and for La-doped ZnO, the band gap shows an increases to 3.457 eV. The calculated band gap approaches the experimental band gap with the implementation of Hubbard U at Ud at Zn and La sites and Up at O sites. The density of states (DOS) of both pure ZnO and La-doped ZnO were conducted to determine the contribution of s, p and d orbitals that appear in the minimum conduction band and maximum valence band. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.