Highly sensitive ultraviolet photodetectors based on ZnO/SnO2 core-shell nanorod arrays

ZnO/SnO2 core-shell nanorod arrays (CSNAs) were synthesized by a facile preparation method. Compared with bare ZnO nanorod arrays (NAs), the near-band-edge photoluminescence (PL) emission was significantly enhanced by coating with SnO2 shell layer. The photoresponse performance of the ultraviolet (UV) photodetector (PD) based on ZnO/SnO2 CSNAs was further investigated. The responsivity and specific detectivity were estimated to be 28.5 (+/- 0.6) A.W-1 and 2.9 (+/- 0.1) x 10(14) cm.Hz(1/2).W-1, which were much better than those of the PD based on bare ZnO NAs. Moreover, the ZnO/SnO2 heterojunction PD also exhibited improved response and recovery times. The localized states introduced by nanocrystalline SnO2 shell layer could effectively prevent the excitons from being trapped by defect states, resulting in the enhancement of the UV emission and photoresponse performance.