Enhancing photoresponsivity of ultraviolet photodetectors based on ZnO/ZnO:Eu (x = 0, 0.2, 1, 5 and 20 at.%) core/shell nanorods

In this work, the effect of europium concentration (0, 0.2, 1, 5 and 20 at.%) as a dopant in the shell of ZnO/ZnO:Eu core/shell nanorods structure was studied and their optical properties were compared with the pure ZnO/ZnO core/shell nanorods structure. The core ZnO nanorods are synthesized by hydrothermal and then encapsulated with ZnO nanorods doped by Eu in different concentration by dip coating method. The encapsulated ZnO nanorods are characterized by scanning electron microscopy (SEM), ultraviolet (UV)-vis spectrophotometry, X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The XRD results showed that the Eu doping decreases the crystallinity of ZnO nanorods. SEM images revealed a well nanorods arrays growth perpendicular to the surface and confirmed the morphological structure of nanorods didn't change by encapsulating. With encapsulating, the diameter of ZnO nanorods increased about 20-40 nm. The UV detecting properties of the nanorods are investigated and the results showed that 1 at.% Eu doping significantly enhances the photo detecting properties.