High quality ZnO–TiO 2 core–shell nanowires for efficient ultraviolet sensing

Abstract

Abstract High quality ZnO–TiO 2 core–shell nanowires (NWs) have been fabricated via a facile two-step method: growth of ZnO nanowires by hydrothermal synthesis and then coating of highly uniform TiO 2 shell using atomic layer deposition (ALD) technique. The ultraviolet (UV) emission intensity of the ZnO–TiO 2 core–shell NWs is largely quenched due to an efficient electron–hole separation that reduces the band-to-band recombinations. To the contrary, the absorption of the ZnO–TiO 2 core–shell NWs in both UV and visible region is enhanced, which is attributed to the antireflection properties of the TiO 2 shell. An UV photodetector fabricated from the ZnO–TiO 2 core–shell NWs showed a maximum photoresponsivity as high as 495 A/W at 373 nm under −10 V, which is ∼8 times higher than that of the photodetector fabricated from bare ZnO NWs. In addition, the transient response of the ZnO–TiO 2 core–shell NWs is improved by 6 times as compared to that of the bare ZnO NWs. The results presented in this work suggest that ZnO–TiO 2 core–shell NWs may be promising for various optoelectronics applications including: UV photodetectors, optical switches, optical fibers and solar cells.