The dependence of the optical properties of ZnO nanorod arrays on their growth time

Abstract

As a multifunctional optoelectronic material, ZnO nanorod array has attracted wide attention. In this work, transparent and highly c-axis oriented ZnO nanorod arrays were grown by a simple chemical solution method using zinc acetate and urea as raw materials. Compared with widely used zinc nitrate and hexamethyltetramine, zinc acetate and urea are safer and cheaper. The relationship between crystallization quality, surface defects, optical properties and growth time of ZnO nanorods was investigated. The results show that with the rise of growth time, the length of ZnO nanorods gradually increases, and the crystalline quality gradually improves. The transmittance in the visible range is gradually enhanced, and the absorption edge near 375 nm becomes steeper. The photoluminescence spectra show that as the growth time increases, the intrinsic emission of the ZnO nanorods, i.e., the ultraviolet emission, is gradually enhanced, and the visible emissions related to the defects are gradually weakened. X-ray photoelectron spectroscopy (XPS) analysis show that the oxygen-related defects on the surface of ZnO nanorods gradually decrease with the increase of growth time, which is consistent with the results of the photoluminescence spectra.