Preparation of Al2O3 dense films using sol derived from Al(NO3)3·9H2O

Abstract

A new sol–gel route has been applied to prepare Al2O3 dense films using Al(NO3)3·9H2O as a raw material and acetylacetone (AcAc) as a chelating agent. The research results show that AcAc and aluminium form a complex compound in the solution, which makes the sol very stable. A small amount of polyvinyl alcohol (PVA) is added to the mixture solution as an anticracking agent. PVA not only decreases effectively the surface tension of the sol but also mitigates the decomposition of the gel films during calcination. The thin films fabricated by spin coating method after sintering at 650°C for 2 h are amorphous. Atomic force microscope and field emission scanning electron microscope images of the films reveal a crack free surface and a dense cross-section. The dielectric films have a low leakage current density in an electric field. To sum up, this new sol–gel route provides a great promising method using cheap inorganic salt Al(NO3)3·9H2O to synthesise the dense alumina thin films.