Effect of Si additions on thermal stability and the phase transition sequence of sputtered amorphous alumina thin films

Journal Article · Wed Jan 14 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4905296· OSTI ID:22412844

Bolvardi, H.; Baben, M. to; Nahif, F.; Schnabel, V.; Shaha, K. P.; Mráz, S.; Schneider, J. M. ^[1]; Bednarcik, J.; Michalikova, J. ^[2]

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1. Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany)
2. Deutsches Elektronen Synchrotron DESY, FS-PE group, Notkestrasse 85, D-22607 Hamburg (Germany)

Si-alloyed amorphous alumina coatings having a silicon concentration of 0 to 2.7 at. % were deposited by combinatorial reactive pulsed DC magnetron sputtering of Al and Al-Si (90-10 at. %) split segments in Ar/O{sub 2} atmosphere. The effect of Si alloying on thermal stability of the as-deposited amorphous alumina thin films and the phase formation sequence was evaluated by using differential scanning calorimetry and X-ray diffraction. The thermal stability window of the amorphous phase containing 2.7 at. % of Si was increased by more than 100 °C compared to that of the unalloyed phase. A similar retarding effect of Si alloying was also observed for the α-Al{sub 2}O{sub 3} formation temperature, which increased by more than 120 °C. While for the latter retardation, the evidence for the presence of SiO{sub 2} at the grain boundaries was presented previously, this obviously cannot explain the stability enhancement reported here for the amorphous phase. Based on density functional theory molecular dynamics simulations and synchrotron X-ray diffraction experiments for amorphous Al{sub 2}O{sub 3} with and without Si incorporation, we suggest that the experimentally identified enhanced thermal stability of amorphous alumina with addition of Si is due to the formation of shorter and stronger Si–O bonds as compared to Al–O bonds.

• OSTI ID: 22412844
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM OXIDES
AMORPHOUS STATE
CALORIMETRY
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CONCENTRATION RATIO
DENSITY FUNCTIONAL METHOD
GRAIN BOUNDARIES
MOLECULAR DYNAMICS METHOD
PHASE TRANSFORMATIONS
SILICON
SILICON ALLOYS
SILICON OXIDES
SPUTTERING
THIN FILMS
X-RAY DIFFRACTION