Role of oxygen vacancies on optical, structural and photoluminescence properties of Sn0.97Cr0.03O2 nanoparticles co-doped with Cu

Abstract

Cu doped Sn0.97Cr0.03O2 nanostructure have been synthesized by chemical co-precipitation method. Phase purity with excellent atomic-level of all ingredient elements and the substitution of Cu in Sn-Cr-O2 host was confirmed by x-ray diffraction (XRD) studies. The elevated crystallite size, lattice parameters, ‘d’ value and volume per unit cell at Cu = 4% recommended that Cu2+ ions with higher ionic radius is replaced in the position of Sn4+ ions of Sn-Cr-Cu-O lattice. Scanning electron microscopic (SEM) images revealed the changed over of hexagon shaped structure to fine and tiny spherical shaped particles by Cu-doping with un-even sized grains. The steady increase of energy gap from 3.51 eV (Cu = 0%) to 3.67 eV (Cu = 4%) is due to the creation of oxygen vacancies and the charge carriers. The modification in infrared band position and intensity confirmed the addition of Cu into the Sn-Cr-O2 lattice. The elevated visible green luminescence (GL) by Cu addition is due to the generation of oxygen vacancies in the inter-band levels which supports the increase of energy gap.