Structure and morphology of aluminium-oxide films formed by thermal oxidation of aluminium

• Published in: Thin solid films 2002-10, Vol.418 (2), p.89-101
• Main Authors: Jeurgens, L.P.H, Sloof, W.G, Tichelaar, F.D, Mittemeijer, E.J
• Format: Article
• Language: English
• Subjects: Aluminium oxide; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Oxidation; Physics; Surface structure; Transmission electron microscopy; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(02)00787-3

The structure and morphology of thin aluminium-oxide films grown by the dry, thermal oxidation of a bare Al(4 3 1) substrate at a partial oxygen pressure of 1.33×10 −4 Pa in the temperature range of 373–773 K were studied using X-ray photoelectron spectroscopy and high resolution electron microscopy. The initial oxidation of the bare Al substrate proceeds by an island-by-layer growth mechanism, involving the lateral diffusion over the bare Al substrate surface of mobile oxygen species. At low temperatures ( T⩽573 K), the mobility of the oxygen species is very low, and an amorphous oxide film of relatively uniform, limiting thickness develops. X-ray photoelectron spectroscopic analysis established the occurrence of a surface-oxide species at the very surface of these films. At higher temperatures ( T>573 K) an initially amorphous oxide film of less uniform thickness develops that gradually transforms into crystalline γ-Al 2O 3. At these temperatures an amorphous-to-γ-Al 2O 3 transition oxide phase occurs.