Ultraviolet photodetectors using hollow p-CuO nanospheres/n-ZnO nanorods with a pn junction structure

• Published in: Sensors and actuators. A. Physical. Vol. 304; p. 111876
• Main Authors: Ji, Yuexing, Jung, Uijin, Xian, Zhanpeng, Kim, Dohyun, Yu, Jiyeon, Park, Jinsub
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-04-2020; Elsevier BV
• Subjects: Annealing; Copper oxides; Electron recombination; Falling; Heterojunctions; Hollow CuO; Nanorods; Nanospheres; P-n junctions; Photometers; Polymers; Sensors; Silicon substrates; Studies; Transfer of spheres monolayer; Ultraviolet detectors; Ultraviolet radiation; UV detector; Zinc oxide; ZnO; UV detector; Transfer of spheres monolayer; ZnO; Hollow CuO
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2020.111876

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•Fabrication of UV detector consisting hollow p-CuO (h-CuO) nanospheres and n-ZnO nanorods (NRs) pn junction structures.•Transferred Cu-ion incorporated polymer converted into h-CuO nanospheres by thermal annealing on the top of n-ZnO NRs.•Ø Coverage of h-CuO nanospheres is controlled by change of transfer times Cu-ion incorporated polymer spheres monolayer.•Ø UV detectors having a 33% coverage of h-CuO spheres showed ∼32.6 times faster response speed than reference samples.
We report on ultraviolet (UV) photodetectors with a pn junction structure consisting of hollow p-CuO (h-CuO) nanospheres and n-ZnO nanorods (NRs). To form the pn junction structure, thermal annealing was conducted using a transferred monolayer of Cu-ion-incorporated polymer spheres onto the n-ZnO NRs/n-Si substrate. Device performance was evaluated by comparing the effects of h-CuO nanosphere coverage changed by sphere shrinkage during thermal annealing of Cu-ion-incorporated polymer spheres. Three samples were prepared by varying the transfer times of h-CuO on ZnO NRs: 0 times (Reference), 1 time (CZ-I), and 2 times (CZ-II). The CZ-II-based UV detector shows a fast rising time of 1.8 s and a falling time of 0.26 s, which are faster rising by 2.2 and 1.3 times and faster falling by 3.1 and 32.6 times than those of the CZ-I and Reference UV detectors, respectively, under illumination with UV light at 254 nm. Moreover, the On/Off current ratio of the CZ-II UV detector is 4.58, which is about 3.3 times and 3.5 times higher than that of the CZ-I and Reference devices, respectively. The higher h-CuO coverage on the ZnO NRs that form the pn junction structure can effectively separate the electron and hole and suppress recombination by mutual transfer of photo-generated electrons and holes in the heterojunction.