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Amorphous alumina thin films deposited on titanium: Interfacial chemistry and thermal oxidation barrier properties
Author(s) -
Baggetto Loïc,
Charvillat Cédric,
Thébault Yannick,
Esvan Jérôme,
Lafont MarieChristine,
Scheid Emmanuel,
Veith Gabriel M.,
Vahlas Constantin
Publication year - 2016
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201532838
Subject(s) - x ray photoelectron spectroscopy , amorphous solid , materials science , atomic layer deposition , selected area diffraction , chemical vapor deposition , chemical engineering , thin film , transmission electron microscopy , titanium , thermal oxidation , stoichiometry , layer (electronics) , bilayer , physical vapor deposition , nanotechnology , chemistry , metallurgy , crystallography , biochemistry , membrane , engineering
Ti/Al 2 O 3 bilayer stacks are used as model systems to investigate the role of atomic layer deposition (ALD) and chemical vapor deposition (CVD) to prepare 30–180 nm thick amorphous alumina films as protective barriers for the medium temperature oxidation (500–600 °C) of titanium, which is employed in aeronautic applications. X‐ray diffraction (XRD), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), and X‐ray photoelectron spectroscopy (XPS) results show that the films produced from the direct liquid injection (DLI) CVD of aluminum tri‐isopropoxide (ATI) are poor oxygen barriers. The films processed using the ALD of trimethylaluminum (TMA) show good barrier properties but an extensive intermixing with Ti which subsequently oxidizes. In contrast, the films prepared from dimethyl aluminum isopropoxide (DMAI) by CVD are excellent oxygen barriers and show little intermixing with Ti. Overall, these measurements correlate the effect of the alumina coating thickness, morphology, and stoichiometry resulting from the preparation method to the oxidation barrier properties, and show that compact and stoichiometric amorphous alumina films offer superior barrier properties.