Observation of 394nm electroluminescence from low-temperature sputtered n-ZnO∕SiO2 thin films on top of the p-GaN heterostructure

The authors report on the 394nm UV light emission from low-temperature sputtered n-ZnO∕SiO2 thin films on top of the p-GaN heterostructure. They compare samples with and without a SiO2 current blocking layer. With a SiO2 layer, electroluminescence spectrum shows a sharp emission peak at 394nm, which is attributed to the recombination of accumulated carriers between n-ZnO∕SiO2 and p-GaN∕SiO2 junctions. As for the sample without a SiO2 layer, a broadband ranging from 400to800nm is observed, which is due to Mg+ deep-level transition in the GaN along with defects in the ZnO layers.