Optical properties and quantum confinement of nanocrystalline II-IV semiconductor particles

Abstract

In this thesis, experiments are described that were performed on suspensions of nanocrystalline II-IV semiconductor particles.The object of this research is to study quantum size effects in relation to the luminescence properties of these particles. A pre-requisite for performing studies of size-dependent optical properties is the availabiblity of monodisperse particles with different particle sizes. In chapter 2 a method is described called size-selective photoetching that provides a way to adjust the particle size in a controlled manner after preparation. With respect to quantum size effects in nanocrystalline II-IV semiconductor particles, the sulphides and selenides are by far the most extensively studied materials. Much less is known about oxidic II-IV semiconductors, of which ZnO is probably the most suitable compound for studies of size-dependent optical properties. The chapters 3-5 of this thesis comprise a variety of luminescence experiments that were performed on nanocrystalline ZnO particles with different sizes. Chapter 6 presents a detailed analysis of the luminescence quantum efficiencies on nanocrystalline CdS and ZnO particles.