Structural and optical characterization of Zn_0.95−xMg_0.05Cu_xO nanoparticles

In the present paper, Mg and Cu co-doped ZnO nanoparticles (Zn_0.95−xMg_0.05Cu_xO) synthesized using Sol–Gel method and their structural, optical properties were studied. Hexagonal wurtzite structure of ZnO was confirmed from XRD results. With Cu doping CuO related phase was formed without altering the crystal structure. The average crystallite size of ZnO decreased with increase of Mg and Cu co-doping. TEM results confirmed the nano size crystalline nature of ZnO nanoparticles. From FE-SEM micrographs, the particle sizes decreased and the morphology became less hexagonal with increase of Cu concentrations along with Mg in ZnO. The weaker and broadened E₂ (high) mode in Raman with increase of Cu doping concentrations may be attributed to wurtzite crystalline structure of ZnO is weakened. Thus, resulting to reduction of the growth induced strains which in good agreement with XRD results. From UV–Vis analysis, fundamental exciton absorption is observed at 377 nm for undoped ZnO. With addition of the dopants (Mg, Cu) the peak got blue shifted from 377 to 355 nm. The blueshift was attributed to the strains produced with dopants but not due to quantum confinement effect due to the sizes of the particles are not comparable of the Bohr atomic radius.