3 years ago

Novel Ω-Shaped Core–Shell Photodetector with High Ultraviolet Selectivity and Enhanced Responsivity

Novel Ω-Shaped Core–Shell Photodetector with High Ultraviolet Selectivity and Enhanced Responsivity
Mingming Jiang, Hongyu Chen, Hongliang Lu, Mingxiang Hu, Yuzhu Gu, Xiaosheng Fang, Feng Teng, Linfeng Hu
The design of nanostructure plays an important role in performance enhancement of low-dimensional optoelectronic devices. Herein, a novel photodetector (PD) based on electrospun SnO2 nanofibers with Ω-shaped ZnO shell (SnO2@ZnO) is fabricated. With 87.4% transmittance at 550 nm, SnO2@ZnO PD exhibits a high photo-to-dark current ratio up to 104 at around 280 nm. Owing to the additional Ω-shaped ZnO shell, SnO2@ZnO PD possesses a responsivity of nearly 100 A W−1 under 5 V bias and the illumination of 250 nm light, which is 30-time enhancement of pristine SnO2 PD. The enhancement is mainly attributed to type-II energy band structure. Furthermore, by changing the direction of incident light, SnO2@ZnO PD has a high UV selectivity with an UV–vis rejection ratio (R250 nm/R400 nm) as much as 2.0 × 103 at 5 V bias under back illumination, which is fourfold higher than that under face illumination. The UV selectivity improvement may be attributed to light confinement in the Ω-shaped structure. With both theoretical simulations and experimental comparisons, it is demonstrated that the unique compact Ω-shaped nanostructure does contribute to photon trapping and gaining process, especially in back-illumination configuration. The approach can be easily extended to other materials, preparing novel building blocks for optoelectronic devices. Combining electrospinning and atomic layer deposition, a novel photodetector based on SnO2 nanofibers @ Ω-shaped ZnO (semi core–shell) is fabricated, resulting in a 30-time enhanced responsivity. The direction of illumination will influence ultraviolet selectivity and back illumination gives a fourfold higher one. The enhancement may be attributed to type-II energy band diagram and light confinement of the unique configuration.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adfm.201704477

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