Anodic oxidation of Ta/Fe alloys

AbstractThe behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammoniumpentaborate electrolyte has been examined by transmission electron microscopy, Rutherfordbackscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray pho-toelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloysare amorphous and featureless and develop at high current efficiency with respective formationratios of 1.67, 1.60 and 1.55 nmV 1 . Anodic oxidation of the alloys proceeds without sig-nificant enrichment of iron in the alloy in the vicinity of the alloy/film interface and withoutoxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similarconcentrations of iron. The higher migration rate of iron species relative to that of tantalumions leads to the formation of an outer iron-rich layer at the film surface. 2003 Elsevier Ltd. All rights reserved. Keywords: Anodic oxidation; Tantalum alloys; TEM; RBS; GDOES; XPS