A novel deposition method to grow ZnO nanorods: Spray pyrolysis

Abstract

ZnO layers were deposited by chemical spray pyrolysis (CSP) using zinc chloride aqueous solutions onto indium tin oxide (ITO) glass substrates at growth temperatures in the region of 400–580 ∘C. The layers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-temperature (T=10K) photoluminescence (PL) measurements. The flat film of ZnO obtained at 400 ∘C evolves to a structured layer by raising the temperature up to 500 ∘C. Deposition around 550 ∘C and above results in a layer comprising well-shaped hexagonal ZnO nanorods with diameter of 100–150 nm and length of up to 1 micron. XRD shows strong c-axis orientation of ZnO being in accordance with the SEM study. Deposition of nanorods was successful using ITO with grain size around 100 nm, whereas on fine-grained ITO (grain size < 50 nm) with smooth surface fat crystals with diameter up to 400 nm and length of about 300 nm were formed. Sharp near band edge (NBE) emission peaks centered at 3.360 and 3.356 eV dominated the PL spectra of ZnO at T=10K, originating from the exciton transition bound to neutral donors. PL and XRD results suggest that ZnO rods prepared by spray pyrolysis are of high optical and crystalline quality.