Blue-light luminescence enhancement and increased band gap from calcium-doped zinc oxide nanoparticle films

Four-fold enhancement in emission in the blue region is observed for the first time from sol–gel deposited calcium doped zinc oxide (Zn1−xCaxO) nanophosphor films having a hexagonal wurtzite structure. A 4.28% increase in the band gap has been obtained by introducing very small concentration (1.47 at%) of Ca dopant. A blue-shift of 55 meV in PL emission in UV region occurs with increase in dopant concentration. Optical transmission, FTIR spectra and surface structure of the films have been studied. Dopant concentration in the films is determined by EDX.