Non-aqueous sol-gel routes applied to atomic layer deposition of oxides

Atomic layer deposition (ALD) is an elegant technique used for the deposition of highly conformal thin films. In ALD, the growth of the film is based on self-limited surface reactions. This enables not only control of the film thickness on the atomic scale, but also offers interesting possibilities to study the mechanisms of the film growth. This Feature Article discusses recent developments and advances in metal oxide thin film deposition based on non-aqueous sol-gel routes applied to ALD. The advantages and drawbacks are compared with respect to water-assisted depositions making use of traditional sol-gel chemistry. In order to better understand the mechanisms involved in film formation, different chemical approaches for metal oxide formation in solution and for thin film growth by ALD will be compared and discussed. Issues that have to be accomplished in order to achieve better control and understanding of thin film formation will also be discussed. In addition, it will be outlined how the use of in situ analytical techniques can provide a more detailed insight into the mechanisms involved in the different growth steps and more generally, on the formation of oxides.