Influence of hydrothermal treatment on morphology and properties of ZnO nanostructures

Abstract

Hydrothermal treatment at low temperature (∼150°C) was performed on different ZnO nanostructures grown on different substrates such as Si and ITO/glass. The water vapor environment and the high pressure of water vapor at that temperature were expected to improve the optical properties of ZnO nanorods. Under such mild condition, no significant morphology changes are expected. However, significant changes were observed in both morphology and optical properties. The morphology of ZnO nanostructures has been changed in various ways, depending on the growth conditions of ZnO nanostructures as well as the substrates. In the terms of optical properties, the increase of photoluminescence (PL) intensity was observed and the UV to visible ratio of ZnO PL spectra was also improved in some cases, while in others there has been no improvement. Hydrothermal treatment was also performed on zinc oxide precursor on Si substrates to study the possible Si contamination during the procedure. Zinc nitrate solution in ethanol was used as the precursor. As a result, an increase of the intensity of the broad peak around 430 nm which is related to silicon oxide was obtained. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).