Abstract
Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current–voltage measurement and UV–vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.
Highlights
Zinc oxide (ZnO) is a versatile n-type semiconducting material owing to the direct bandgap (3.37 eV)
Ordered zinc oxide nanorods (ZnO NRs) with excellent electrical conductivity give higher surface reaction activity for a bio-interfacing platform for immobilization, which could lead to greater signal transductions during the detection, promise better sensing performance
The increment of immersion time resulted in a higher density of grown ZnO NRs, developed more interconnection between them
Summary
Zinc oxide (ZnO) is a versatile n-type semiconducting material owing to the direct bandgap (3.37 eV)with a large exciton binding energy (60 meV) at room temperature, bio-safe, functional biocompatible, and high isoelectric point (~9.5) [1,2]. Several methods have been developed to synthesize ZnO nanostructures, such as pulsed laser deposition (PLD), physical vapor deposition (PVD), chemical vapor deposition (CVD), carbothermal reduction method, and hydrothermal method [14,15,16,17,18,19]. These methods (such as PLD, PVD and CVD) require a high vacuum chamber and more complex set up to deposit ZnO thin film. The hydrothermal method offers simplest preparation set-up with less energy consumption, and low production cost, where the
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