Violet-blue-green emission and shift in Mg-doped ZnO films with different ratios of oxygen to argon gas flow

► By magnetron sputtering technique, Mg-doped ZnO films were prepared. ► Crystal structures and surface morphology of Mg-doped ZnO films were discussed. ► Optical properties in Mg-doped ZnO films were systematically investigated. ► Spectral shift of violet-blue emission was discussed in detail.