Manganese(II) in Semiconductor Nanocrystals

Abstract

The following chapters describe the state of II-VI semiconductor nanocrystal preparation. Introduction of transition metal dopants gave rise to new materials and provided an insight into both physical and chemical properties of these semiconductor nanocrystals. Mn(II) and Co(II) dopants were used to probe the spatial position of an exciton inside Mn(II):ZnSe/CdSe core/shell nanocrystals and to show that p-d exchange still dominates s-d exchange, consistent with bulk analogues. Energy transfer between Mn(II) and excitonic states in Mn(II):ZnSe/CdZnSe with various compositions was shown to result in temperature dependent dual emission. The use of multishell ZnS/CdS/ZnS heterostructures, were shown to give both stability against chemical degradation and allowed tunability of the excitonic states. The discovery of a method to completely suppress Ostwald ripening at temperatures that still allow cations to assume their thermodynamic distributions inside the samples has laid the first step in the coming revolution of nanocrystal synthesis. Independent control over morphology and composition has settled the debate on "doping impossibility" and nanocrystals seen through the new Overton window can be placed in a dynamic equilibrium with their environment.