Growth and properties of alumina films obtained by low-pressure metal–organic chemical vapor deposition

Amorphous alumina films with a film thickness of 0.35–2.0 μm were prepared on glass and silicon substrates by low-pressure metal–organic chemical vapor deposition using aluminum tri-sec-butoxide (ATSB) and argon. These films were studied by choosing different substrate temperatures and amounts of argon carrier gas through ATSB vaporizer [Ar(ATSB) flow rate]. Films deposited at low temperatures with a high Ar(ATSB) flow rate showed cracked surfaces. The kinetic study was focused on the growth rate, apparent activation energy and ATSB reaction order. No carbon was detected for films deposited in an argon atmosphere. The film had a higher compositional Al/O ratio at higher deposition temperatures. The microstructure of the alumina deposited was observed using scanning electron microscopy and atomic force microscopy. Mechanical properties, i.e. hardness, internal stress and adhesion of the alumina films, were evaluated. Optical properties, i.e. refractive index and optical transmittance, were also measured.