Organometallic vapour deposition of crystalline aluminium oxide films on stainless steel substrates

The organometallic vapour deposition of aluminium oxide films in a cold wall reactor was studied at temperatures between 773 and 1273 K and the pressure range of 55–1000 hPa. Aluminium acetylacetonate and oxygen were used as precursors. All films were characterized by scanning electron microscopy, electron dispersive X-ray spectroscopy and X-ray diffraction. Film growth at low pressure (55 hPa) was analyzed as a function of the deposition temperature: It is mainly surface kinetically controlled, and films grown at low temperatures ( 2 O 3 , θ-Al 2 O 3 , and α-Al 2 O 3 . These crystalline films are spalling. In addition, the influence of the total pressure on the deposition was studied for high deposition temperatures (1273 K): Film growth was significantly faster at pressures below 300 hPa. Additionally, a phase change is observed with increasing pressure: Films deposited at 55 hPa consist of three phases, γ-Al 2 O 3 , θ-Al 2 O 3 , and α-Al 2 O 3, whereas above 200 hPa mainly the latter two phases are observed. Films grown at high pressures above 200 hPa are better adhering.