Raman Spectroscopic Study of the ZnO Nanostructures

Abstract

A variety of Zinc Oxide (ZnO) nanostructures such as nanowires, nanospheres, nanorods, flower-like, tubules and tetrapods were synthesized via thermal evaporation process using Zn and ZnO precursors in a tube furnace. The structural and optical properties of the as grown structures were characterized by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Raman spectroscopic results for the nanostructures in comparison with the recent developed theory and well established experimental data are reported. We have observed significant Raman shifts for these ZnO nanostructures in the typical Raman-active modes assigned to ZnO. The main peak known as E2(High), which is the finger print of wurtzite crystal structures, show remarkable blue-shifts for these nanostructures when compared with the theoretical and experimental results. The Raman shifts in the typical Raman-active modes is usually reported towards the higher wave numbers which is regarded the characteristics of the nanostructures. But we have also observed the Raman shifts towards lower wave numbers for some of the typical Raman-active modes in various morphologies.