Efect of thickness and reaction media on properties of ZnO thin flms by SILAR

Abstract

Zinc oxide (ZnO) is one of the most promising metal oxide semiconductor materials, particularly for optical and gas sensing applications. The infuence of thickness and solvent on various features of ZnO thin flms deposited at ambient temperature and barometric pressure by the sequential ionic layer adsorption and reaction method (SILAR) was carefully studied in this work. Ethanol and distilled water (DW) were alternatively used as a solvent for preparation of ZnO precursor solution. Superfcial morphology, crystallite structure, optical and electrical characteristics of the thin flms of various thickness are examined applying X-ray difraction (XRD) system, scanning electron microscopy, the atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Hall efect measurement analysis and UV response study. XRD analysis confrmed that thin flms fabricated using ethanol or DW precursor solvents are hexagonal wurtzite ZnO with a preferred growth orientation (002). Furthermore, it was found that thin flms made using ethanol are as highly crystalline as thin flms made using DW. ZnO thin flms prepared using aqueous solutions possess high optical band gaps. However, flms prepared with ethanol solvent have low resistivity (10–2 Ω cm) and high electron mobility (750 ­cm2 /Vs). The ethanol solvent-based SILAR method opens opportunities to synthase high quality ZnO thin flms for various potential applications.