Aluminium tri-iso-propoxide: Shelf life, transport properties, and decomposition kinetics for the low temperature processing of aluminium oxide-based coatings

Abstract

Aluminium tri-iso-propoxide (ATI) is a common precursor for the MOCVD of alumina coatings. However, little is known on its long term stability while its saturated vapour pressure in function of the temperature is controversial. The present contribution deals with these questions through FTIR, TGA and vapour pressure measurements. Low pressure MOCVD from ATI was performed in the temperature range 250–700 °C. Whereas the pyrolytic decomposition of ATI leads to hydroxo species free alumina films above 415 °C, it is shown in this paper that the thermal decomposition of ATI in the presence of water vapour yields pure alumina films at temperatures as low as 300–350 °C. The films prepared in the range 250–700 °C do not diffract X-rays. Arrhenius plots for both pyrolytic (Ea∼12 kJ/mole) and water assisted (Ea∼9 kJ/mole) decomposition reveal diffusion-limited processes with higher growth rate values in the former case.