Photoluminescent properties of Cu-doped ZnO thin films

Zinc oxide films doped with various contents of copper were deposited on silicon (111) substrates by rf reactive sputtering. The photoluminescent(PL) spectra of the ZnO films were measuered at room temperature. Results showed that each of the samples had a blue band at about 435nm (2.85eV) and the intensities of these blue bands were changed with the variation of content and sputtering power. It was observed that there is a stronger blue bi-peak when the power reaches 150W and the copper content is equal to 2.5%, and there is a stronger blue peak at 437?nm when the power was 100?W and copper content is 1.5% on the PL spectra of ZnO films, the latter had a good c axis orientation. We have investigated the PL properties for various Cu-doped contents and different sputtering powers, and the mechanism of blue emission was also discussed in this paper.