Doping-induced electron density modification at lattice sites of ZnO:Ga nanostructures: effects on vibrational and optical properties

Abstract

Effects of Ga doping on the morphology, microstructure, electron density distribution, and optical properties of hydrothermally grown ZnO nanostructures have been studied by means of scanning electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction, and the maximum entropy methods. It has been shown that while Ga incorporation in ZnO lattice does not result in a large distortion of its wurtzite structure, it affects substantially the electronic charge distribution along the Zn–O bonds. Anisotropic redistribution of the electron charge density around the cation sites consolidates the assumption that the Ga atoms in doped nanostructures incorporate by substituting Zn atoms. The formation of a high density of point defects modifies the lattice dynamics of ZnO; in addition, it introduces a pronounced band-tail in the forbidden band gap.