Some factors affecting the properties of sputter-deposited NiTi-based shape memory alloy thin films

Xu Huang; Yong Liu

doi:10.1117/12.468642

13 November 2002 Some factors affecting the properties of sputter deposited NiTi-based shape memory alloy thin films

Xu Huang, Yong Liu

Proceedings Volume 4934, Smart Materials II; (2002) https://doi.org/10.1117/12.468642
Event: SPIE's International Symposium on Smart Materials, Nano-, and Micro- Smart Systems, 2002, Melbourne, Australia

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 SiO₂buffer 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.

Citation Download Citation

Xu Huang and Yong Liu "Some factors affecting the properties of sputter deposited NiTi-based shape memory alloy thin films", Proc. SPIE 4934, Smart Materials II, (13 November 2002); https://doi.org/10.1117/12.468642

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