Room-temperature ferromagnetism in the large and direct bandgap diluted magnetic semiconductor zinc oxide (ZnO) is attributed to the intrinsic defects and p-orbital–p-orbital (p–p) coupling interaction.

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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.

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Zinc oxide is a unique n-type semiconducting material, owing to wide bandgap of ~3.37 eV, non-toxic, bio-safe and biocompatible with high isoelectric point of ~9.5, make it as promising biomaterial to be utilized as sensing matrix in biosensor applications. In addition, ZnO that possess high electron affinity provide a good conduction pathway for the electrons hence result in significant electrical signal change upon detection to target biomolecules. Moreover, high surface area of ZnO nanorod enhance immobilization of enzymes, hence, increase the device performance. Field effect transistor (FET)-based biosensor offer simplicity in handling and label-free, has also become research topic among researchers for novel biosensor development. This review aims to explore the preparation of ZnO nanorod using hydrothermal method and investigate the fabrication of ZnO nanorod-based FET biosensor. Thus, contribute to enhance understanding towards biosensor development for health monitoring, especially based on FETs structure devices.