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Proceedings Paper

Some factors affecting the properties of sputter-deposited NiTi-based shape memory alloy thin films
Author(s): Xu Huang; Yong Liu
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Paper Abstract

Several factors affecting the surface morphology, transformation characteristics and shape recovery of co-sputtered NiTi-based shape memory alloy thin films were investigated. It is found that the Ar gas pressure, substrate orientation, deposition temperature and annealing condition all affect the surface morphology. In particular, when under high Argon gas pressure, the deposited film contains surface cracks, while the film is smooth and dense if a 2.3mTorr Argon gas pressure was used during deposition. The film deposited at 450°C on a (100) Si substrate has a rough surface associated with a large distribution of island sizes. Post-annealing treatment leads to a more homogeneous distribution of island dimensions and a smoother surface. On the other hand, the films deposited at 450°C on a (111) Si substrate or on a SiO2 buffer layer have more homogeneous island sizes. It is also found that both the substrate orientation and the SiO2 buffer layer dramatically affect the transformation behavior and shape recovery magnitude. Film deposited on (100) Si has a higher recovery strain than that deposited on (111) Si under the same stress. The oxygen in SiO2 buffer layer may have deteriorated the deposited film, which results in a very low shape recovery strain. Interfacial stress between the substrate and the thin films is found to lower the transformation hysteresis.

Paper Details

Date Published: 13 November 2002
PDF: 9 pages
Proc. SPIE 4934, Smart Materials II, (13 November 2002); doi: 10.1117/12.468642
Show Author Affiliations
Xu Huang, Nanyang Technological Univ. (Singapore)
Yong Liu, Nanyang Technological Univ. (Singapore)

Published in SPIE Proceedings Vol. 4934:
Smart Materials II
Alan R. Wilson, Editor(s)

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