Gas phase synthesis of ionic solid solutions-crystalline bulk materials and thin films

Abstract

Solid solutions play a significant role in recent research and technology. In semiconductor technology provisioning as well as the substitution in the host lattice are used to generate certain electrical properties ("band gap engineering"). In addition the optical properties of solids can be changed by substitution. This applies to both absorption and emission behaviour, for example, in phosphors. This is achieved by doping with a suitable activator ion or a substitution in the host lattice. To produce ionic solid solutions different methods are in use. Mass-produced articles such as fluorescent substances are primarily synthesised in aqueous solutions, followed by drying and calcining if necessary. Furthermore, single crystals are of interest for fundamental studies. In semiconductor technology thin films are important. These are usually deposited by various gas phase processes. In this work we report • Chemical vapour transport (CVT) of solid solutions, a process for the gas phase synthesis of bulk materials (single crystals). • Sputter techniques for thin film production. • Pulsed laser deposition (PLD) as another method to produce thin layers. Whereas literature is focused on cation substitution in ionic compounds only little work is focused on anion substitution. This work concentrates on the anion substitution, but the basic principles and treatment processes apply to cation substitution as well. 1. Chemical vapour transport. 2. Sputter techniques. 3. Pulsed laser deposition.