Route from ZnO Thin Films to Nanostructures on Si Substrates by Metal Organic Chemical Vapor Deposition

Abstract

ZnO thin lms and nanostructures were grown on Si substrates in a metal organic chemical vapor deposition (MOCVD) process as a function of growth conditions including source ow rates and growth temperatures. ZnO thin lms with smooth surface morphology were grown in growth conditions with low zinc source ow rates and high growth temperatures. On the other hand, the surface morphology of thin lms became dramatically rough on increasing the ow rate of the zinc source, resulting in the formation of various kinds of nanostructures such as nanorods, nanotowers, and nanocactuses, depending on the MOCVD growth temperature. This result is mainly due to the strong tendency of ZnO toward a three-dimensional (3D) growth mode with higher ow rates of the zinc source in a MOCVD process, indicating that a route from thin lms to nanostructures relies on the 3D growth behavior of ZnO.