Effects of Co doping on the structural and optical properties of ZnCuO thin films

• Oxygen vacancies in the Zn0.95Cu0.05O films increase with the Co doping level.
• The introduction of Co ions causes Cu2+ to Cu+ as the Co concentration level exceeds 1%.
• The Eg of Zn0.95Cu0.05O films shows a blue shift with increasing Co doping level.

Effects of Co doping concentration on the microstructure and the photoluminescent properties of Zn0.95Cu0.05O thin films synthesized by a sol–gel method were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, room-temperature photoluminescence, UV transmission spectrometer. An analysis of the O 1s peak of ZnO film showed that the concentration of oxygen vacancies increases with the Co doping level. We also revealed that the introduction of Co ions causes the valence state of Cu to change from +2 to +1 as the Co concentration level exceeds 1%. The Eg of Zn0.95Cu0.05O films shows a blueshift from 3.01 to 3.14 eV with increasing Co doping level.