Synthesis of oxide thin films and overlayers by atomic layer epitaxy for advanced applications

Atomic layer epitaxy (ALE) as a self-limiting thin film growth process results in several practical advantages including accurate and simple thickness control, large area and large batch capability, good conformality and reproducibility, straightforward doping and scale-up, possibility to produce sharp and tailored interfaces as well as capability to prepare multilayer structures in a continuous process. In this paper the use of ALE in deposition of numerous conducting and insulating oxide thin films will be reviewed. The versatile ALE chemistry allows the use of different types of metal-containing precursors from simple inorganic compounds to organometallics. Commonly used oxygen sources include water, oxygen, ozone, hydrogen peroxide and alcohols. The recent advances in oxide ALE processes, i.e. deposition of ternary and quaternary oxides, controlled doping of transparent conductors, preparation of multilayer structures as well as conformal coating of porous silicon will also be discussed in respect to their practical applications.