CONTROLLED GROWTH OF HIGHLY ORIENTED ZnO NANOROD ARRAY ON AMORPHOUS GLASS SUBSTRATE AND THEIR OPTICAL AND ELECTRICAL PROPERTIES

Abstract

Highly oriented zinc oxide nanorod array is fabricated on ZnO quantum dots functionalized amorphous glass substrate. Simplified aqueous based beaker-chemistry is utilized for a controlled growth of vertically oriented nanorod arrays. XRD studies exhibit (002) orientation of the nanorod arrays which are achieved by sheer control of parameters such as ZnO seed layer morphology, molarity, reaction time and deposition temperature. A lower concentration of precursor leads to the sparse nanorods alignment while a higher concentration renders a (002) oriented of nanorod array film. We find that the amorphous substrate plays no role and a pre-annealed quantum dot array leads to an oriented structure when the growth is faster and the quantum dot surface provides an optimal site for oriented growth. The photoluminescence (PL) spectra reflect a strong UV emission at 380 nm and a broad green orange emission band nearly 600 nm which is generally attributed to the defect band transition. UV-visible spectra has a sharp jump at 380 nm for the excitonic band absorptions. The DC conductivity measurement reveals that the film is a good semiconductor (order of σ = 10-7 ohm-1 cm-1) and provides a very promising platform for photovoltaic and optoelectronic device applications. The conductivity of the ZnO nanorod array becomes higher in orders of 10 with the illumination of UV light of the 350 nm wavelength.