Luminescence Properties of Nitrogen-Doped ZnO

Pure and nitrogen-doped ZnO films are prepared on a Au(111) single crystal and characterized by luminescence spectroscopy in a scanning tunneling microscope. In both cases, a 730 nm defect peak is revealed in addition to the band recombination peak at 373 nm. The intensity of the defect peak increases when growing the film at reducing conditions or inserting nitrogen into the oxide lattice. Our finding suggests that not the nitrogen impurities but O vacancies are responsible for the defect emission and that the nitrogen incorporation only facilitates the formation of O defects.