Browsing by Author "Alenezi, Mohammad R."
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Item Open Access Hierarchical zinc oxide nanobrushes ultraviolet photodetector(Wiley for Institution of Engineering and Technology (IET), 2022-07-12) Alenezi, Mohammad R.; Almeshal, Abdullah M.; Alkhaledi, Abdullah N. F. N. R.In order to synthesise hierarchical zinc oxide (ZnO) nanomaterials with a high surface-to-volume ratio, a well-controlled multistage hydrothermal method was developed. Hierarchical ZnO nanobrushes (ZNBs) built from initial mono-morphological nanomaterials, ZnO nanowires (ZNWs), and ZnO nanoplates (ZNPs) were developed using sequential nucleation and growth following a hydrothermal process. Hierarchical nanomaterials which are comprised of one-dimensional (1D) nanowire building blocks were obtained via a zinc ion source (zinc nitrate) during the second growth phase. In comparison to their first mono-morphological equivalents, the hierarchical nanomaterials which were grown showed improved ultraviolet (UV) detection, as well as improved sensitivity (∼104), an ultra-fast response time (235 ms), and a good recovery time (310 ms). Improvements to the response and recovery times were a result of distinct nanojunction barrier-dominated resistance. Moreover, the enhanced sensitivity of the ZNB photodetector (PD) was because of the reduced dimensionality and the ultrahigh surface-to-volume ratio. This work lays the groundwork for lower-cost, larger-scale, and lower-temperature production of high-performance nanostructured ZnO-based PDs on transparent and flexible substrates.Item Open Access ZnO nanoleaves with superior photodetection properties(Royal Society of Chemistry, 2022-07-19) Alenezi, Mohammad R.; Almeshal, Abdullah M.; Alkhaledi, Abdullah N. F. N. R.Controlled multiphase hydrothermal synthesis technique was developed to design and grow hierarchical zinc oxide (ZnO) nanostructures with high surface-to-volume ratio. ZnO nanoleaves (ZNLs) and nanoflakes (ZNFs) assembled from initial monomorphological nanostructures, ZnO nanowires (ZNWs), and ZnO nanodiscs (ZNDs), respectively. These hierarchical nanostructures with 2D nanosheets building blocks were obtained by sequential nucleation and growth following a hydrothermal process. Zinc sulphate was the source of zinc ions in the second growth phase. In comparison to their monomorphological counterparts, the hierarchically designed ZnO nanostructures demonstrated superior ultraviolet detection properties, an improved photosensitivity (∼105), and fast response-time (5 s) and fast recovery-time (1 s). The enhancement in photosensitivity of the ZNLs photodetector was ascribed to the reduced dimensions and increased surface-to-volume ratio. This work is part of the efforts leading the way toward low cost, large scale, and low temperature fabrication of high performance nanostructured ZnO PDs on flexible and transparent substrates.