The effect of growth temperature of seed layer on the structural and optical properties of ZnO nanorods

• ZnO nanorods have been synthesized by hydrothermal method by using ZnO seed layer on ITO coated glass substrate.
• The growth temperature of the ZnO seed layer has been varied from 150 to 550 °C.
• The growth temperature of the ZnO seed layer influences the structural and optical properties of the as-grown nanorods.
• The seed layer grown at 350 °C promotes vertical growth of ZnO nanorods with high crystallinity and improved UV emission.
• The growth kinetics of the ZnO seed layer at different temperatures has been discussed.

The structural and optical properties of ZnO nanorods are investigated as a function of growth temperature of the seed layer. The seed layer comprising of ZnO nanocrystallites is grown on ITO substrates at five different temperatures (150–550 °C) and the nanorods are grown on the seed layer by the facile hydrothermal method. The seed layer grown at 350 °C is observed to be uniformly textured with c-axis orientation leading to the synthesis of vertically aligned nanorods with smaller diameter. The HR-TEM analysis and the intense peak along (002) direction in the XRD spectra of this sample implied that the nanorods possess c-axis orientation. An enhanced UV emission is also observed in the photoluminescence spectra of this sample. The diversity in the morphology and orientation of the seeds at different temperatures has been explained by the growth kinetics of the ZnO nanocrystallites.