Hydrothermal growth of flower-like ZnO nanostructures on porous silicon substrate

• We synthesized ZnO nanoflowers grown on a spin-coated ZnO/porous silicon substrate by using a hydrothermal approach.
• Effect of precursor concentration on deformation of flower-like nanostructures is investigated.
• We report a UV emission shifts toward lower wavelengths due to the shape transition and size increment of ZnO nanoflowers.

Flower-like zinc oxide (ZnO) nanostructures were successfully synthesized on porous silicon substrates using a simple hydrothermal method. The characteristics of the ZnO nanostructures were investigated through field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and photoluminescence (PL). FESEM images revealed shape transitions from nanoflowers comprising nanoparticles to well-faceted hexagonal ZnO nanostructures when the precursor molarity increased from 0.01 to 0.20 M. The strong intensity and narrow width of XRD peaks indicate that ZnO nanostructures with high molarities have good crystallinity. The PL spectra indicate that ultraviolet emissions shift slightly toward lower wavelengths with increasing precursor solution molarity and that the intensity increases with improvement in ZnO crystallization.