AbstractAmorphous (Al2O3)x(SiO2)ythin films have been grown by atmospheric pressure metal‐organic chemical vapour deposition using the single‐source precursor [Al(OSiEt3)3]2. Characterisation by X‐ray photoelectron spectroscopy indicated that the films consisted of a mixture of Al2O3, SiO2and an aluminosilicate. The relative amount of each species was dependent on the deposition temperature and the carrier gas composition. Use of NH3as the carrier gas resulted in the increased volatility of the precursor by thein situformation of the low‐melting Lewis acid–base adduct Al(OSiEt3)3(NH3); however, no nitrogen incorporation was observed in these deposi