Optimization of seed layer thickness for the growth of the one dimensional vertically oriented ZnO nanowires

In this study, ZnO nanowires were grown using chemical bath deposition on top of spray-coated seed layers ranging from 20 to 60 nm in thickness. The effect of seed layer thickness on structural, morphological and optical properties of ZnO nanowires was studied using characterization techniques such as XRD, SEM, and UV–Vis spectroscopy, respectively. The XRD analysis showed that all the nanowires grown on different seed layer thicknesses were hexagonal and preferentially oriented (002) plane. According to the SEM analysis, all the nanowires were vertically oriented. The diameter of the nanowires varied between 47 and 100 nm, and the length ranged typically from 1.03 to 1.78 m. The bandgap of ZnO nanowires redshift from 2.56 to 3.22 eV with the decrement of seed layer thickness. The H _2 gas sensing behaviour of the fabricated sensor prototype using deposited nanowires was investigated at 150 ^∘ C. The optimum response for H _2 gas was obtained for the ZnO nanowires grown on the seed layer thickness of 35 nm.