An investigation into the growth conditions and defect states of laminar ZnOnanostructures

Abstract

The variation in morphology of zinc oxide when it crystallises is one of the fascinating aspects of this important semiconductor. Alterations in hydrothermal growth conditions can allow the synthesis of a wide range of shapes and structures, including nanowires and layered structures, formed via a secondary growth regime but, to date, little work has investigated the effect changes in growth conditions can have and their influence on the optical properties. Here, systematic changes in growth conditions and reactants were carried out and the results studied using scanning electron microscopy, X-ray diffraction, optical transmission, cathodoluminescence and Raman spectroscopy and atomic force microscopy. We demonstrate that the choice of the reactants can have a significant effect not just on the morphologies of the structure, but on the fundamental properties of the crystalline state such as alterations into the defect states within the system. Furthermore, secondary growth is shown to be dependent on the underlying primary growth morphology, and general reaction conditions for laminar growth are suggested.