![]() Zinc oxide (ZnO) is a n-type semiconductor with a wide band gap (3.37 eV), a 60 meV exciton binding energy 29. It is also highly versatile and easy to prepare material, suitable for applications in field effect transistors 24, photodetectors 25, light emitting diodes 26, solar cells 27, photocatalysis 28, etc. with applications in photodetectors have been reported.Ĭopper oxide (CuO) is a p-type semiconductor with a narrow band gap in the range of 1.2–2.1 eV 23, and high optical absorption in the visible range. Hence, radial core–shell nanowire arrays based on ZnO–Cu xO 16, ZnO/CuCrO 2 17, ZnO/WS 2 18, ZnO–Cu 2O 19, ZnO–Co 3O 4 20, ZnO/ZnS 21, CdSe/ZnTe 22, etc. Thus, these radial core–shell heterostructure nanowires can be regarded as “smart materials” with controlled interfaces and enhanced multi-functionalities that can lead to the development of the next-generation high-performance optoelectronic devices 14, 15, 16. In this type of heterojunction, charge separation region is distributed over the radius of the nanowire, which is significantly smaller than its length leading to an improved collection at the electrodes 14. Amidst them, radial core–shell heterostructure nanowires obtained using two semiconductors arranged in a type II (staggered gap) band alignment augmenting the charge carrier separation efficiency. Additionally, the progress made in tuning the material properties during their synthesis led to the development of heterostructure nanowires with different architectures, such as axial, radial or branched 11, 12, 13. These lead to an increase of the light confinement and photosensitivity 6, features essential for applications such as photodetectors 7, lasers 8, solar cells 9, photocatalysis 10, etc. Nanowires are a particularly remarkable class of nanostructures owed to specific properties such as their one-dimensional geometry and large surface-to-volume ratio. Due to their unique physico-chemical properties 2, widespread research efforts are focused on the use of semiconductor nanowires as the new building blocks for functional devices in various fields which include optoelectronics 3, biosensors 4, spintronics 5, etc. Given the increasing demand for continuous miniaturization and reduced energy consumption, nanoscale optoelectronic devices based on semiconductor nanowires are emerging as an important novel class of devices with enhanced performances and improved or even new functionalities 1. The results highlighted that the obtained CuO–ZnO core–shell nanowires are emerging as potential building blocks for a next generation of photodetector devices. The performance of the photodetector device was evaluated by assessing its key parameters: responsivity, external quantum efficiency and detectivity. The photoelectrical properties emphasize that the p–n radial heterojunction diodes based on single CuO–ZnO core–shell nanowires behave as photodetectors, evidencing a time-depending photoresponse under illumination at 520 nm and 405 nm wavelengths. In order to analyse the electrical and photoelectrical properties of the metal oxide nanowires, single CuO and CuO–ZnO core–shell nanowires were contacted by employing electron beam lithography (EBL) and focused ion beam induced deposition (FIBID). The morphological, structural, optical and compositional properties of the CuO–ZnO core–shell nanowire arrays were investigated. ![]() ![]() CuO–ZnO core–shell radial heterojunction nanowire arrays were obtained by a simple route which implies two cost-effective methods: thermal oxidation in air for preparing CuO nanowire arrays, acting as a p-type core and RF magnetron sputtering for coating the surface of the CuO nanowires with a ZnO thin film, acting as a n-type shell. ![]()
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