Aqueous precursor systems

Abstract

In this chapter, water based CSD of electronic oxide films from carboxylate based precursors is discussed which has, besides the absence of hazardous solvents, the additional asset of simple and inexpensive synthesis- and deposition equipment. However very attractive, this 'new' CSD method had to deal with typical scientific and technological obstacles. First of all, the development of water soluble precursors, especially when high valent metal ions are involved, in a chemical environment suitable for gel formation and film deposition forms a true chemical challenge. A second obstacle is the difficulty to deposit homogeneous thin layers of water based precursor solutions, which is related with wetting incompatibilities. Both issues will be elaborately discussed and reviewed. Moreover it is shown that film properties can be drastically optimized by means of controlling all different processing steps. Finally the achievement of highly demanding challenges such as deposition of epitaxial or ultrathin layers is demonstrated. The aqueous CSD method can therefore be considered as a fairly mature technique enabling the deposition of oxide layers for state of the art applications and providing a means for the fast screening of highly advanced materials systems and processes.