A new method to experimentally determine the thermal expansion coefficient, Poisson’s ratio and Young’s modulus of thin films
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The objective of this letter is to present a novel procedure to determine the thermal expansion coefficient, the Poisson’s ratio, and the Young’s modulus of a thin film deposited only on one substrate. The internal film stress (σf), thermal expansion coefficient (CTE, αf), Poisson’s ratio (νf), and Young’s modulus (Ef) of metal oxide films are very important in optical devices. These parameters are affected by the deposition method and deposition conditions, which could have a significant impact on the device applicability and reliability . In addition, the mechanical properties and the internal stress of thin films differ significantly from those of bulk materials due to the effects of interfaces, microstructure, and underlying substrates. Hence, when there is a need to know αf, νf, and Efof deposited films, it is necessary to determine them directly on the film, a process generally involving the measurement of the internal film stress, which may be so high that in some cases the...
KeywordsThermal Expansion Coefficient Niobium Oxide Intrinsic Stress Tantalum Oxide Film Stress
This work was performed in the Engineering Physics Department at Ecole Polytechnique of Montreal, Canada. The author would like to thank Prof. S. Goldsmith and Prof. R.L Boxman for a critical reading of the manuscript and helpful discussions.
- 8.Bunshah RF (2001) Handbook of hard coatings. Noyes Publications, NY, p 248Google Scholar