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

AbstractThe structure and morphology of thin aluminium-oxide films grown by the dry, thermal oxidation of a bare Al (431) substrateat a partial oxygen pressure of 1.33 =10 Pa in the temperature range of 373–773 K were studied using X-ray photoelectron y4 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 lowtemperatures ( 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 atthe very surface of these films.At higher temperatures( T )573 K ) an initially amorphous oxide film of less uniform thicknessdevelops that gradually transforms into crystalline g-Al O .At these temperatures an amorphous-to- 23 23 g-Al O transition oxidephase occurs. 2002 Elsevier Science B.V. All rights reserved.