Aluminum-nitrogen co-doping improves the blue emission of ZnO films: A combined theoretical-experimental study

The investigation on visible emission of ZnO is necessary due its potential application in electrochemical communication, biosensor, and white light diodes, and so forth. Previous report indicates that the visible light of ZnO is related to the defect type and concentration. It can be regulated by various methods. However, quenching of light emission occurs if too many defects are introduced. In this work, combined with theoretical calculation about energy band structure, aluminum-nitrogen co-doped ZnO is conducive to form p-type semiconductor, but aluminum doped ZnO films tend to form a deep n-type semiconductors. Therefore, in the experiment, aluminum-nitrogen co-doped ZnO films are prepared using radio frequency magnetron sputtering. The substitution of oxygen using nitrogen impurity is expected to introduce more oxygen vacancies and interstitial zinc defects related to visible light emission. At the same time, annealing in vacuum is also a highly non-equilibrium processes with low oxygen and high zinc contents. Results indicate that combined with aluminum-nitrogen co-doping and an appropriate annealing temperature, the blue and blue-green emission of ZnO films can be greatly improved.