Low temperature and large-scale growth of ZnO nanoneedle arrays with enhanced optical and surface-enhanced Raman scattering properties

Large-scale ZnO nanoneedle arrays have been grown on four-inch silicon wafers with ZnO seed film by an aqueous chemical growth method at a low growth temperature and short reaction time. The volumes of 1,3 diaminopropane play an important role in controlling the dimension and optical emission properties of ZnO nanoneedle arrays, which exhibit a very prominent green emission and weak UV emission from defect and band gaps in the cathodoluminescence spectrum, respectively. The ZnO nanoneedle arrays with large alignment variations display broadband and omnidirectional antireflection properties from the gradual index profile, and can provide a higher surface-to-volume ratio and stronger defect emission, which results in a peak photocatalytic performance at a light irradiation of 10 W UV. The appropriate Ag sputtering durations on the ZnO nanoneedle arrays have been optimized to yield the greatest surface-enhanced Raman scattering effect in the rhodamine 6G molecule. The ZnO/Ag composite arrays provide a facile, high enhancement, low detection limit and low cost fabrication, which shall be of significant value for practical applications of other SERS sensing systems.

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