Investigation of the Crystalline Orientations and Substrates Dependence on Mechanical Properties of PZT Thin Films by Na
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1129-V11-05
Investigation of the Crystalline Orientations and Substrates Dependence on Mechanical Properties of PZT Thin Films by Nanoindentation Dan Liu, Sang H. Yoon, Bo Zhou, Barton C. Prorok and Dong-Joo Kim Materials Research and Education Center, Auburn University, AL 36849, USA ABSTRACT In this paper, we investigated the effects of the substrates and crystalline orientations on the mechanical properties of Pb(Zr0.52Ti0.48)O3 thin films. The PZT thin films were deposited by sol-gel method on platinized silicon substrates with different types of layer materials such as silicon nitride and silicon oxide. The crystalline orientations of PZT thin films were controlled by combined parameters of a chelating agent and pyrolysis temperature. A nanoindentation CSM (continuous stiffness measurement) technique was employed to characterize the mechanical properties of those PZT thin films. It was observed that (001/100)-oriented films show a higher Young’s modulus compared to films with mixed orientations of (110) and (111), indicating a clear dependence on film orientation. The influence of substrates on the mechanical properties of PZT thin films was also characterized. Finally, no significant influence of the film thickness was found on the mechanical properties of films thicker than 200 nm. INTRODUCTION PZT thin films are widely used in microelectromechanical (MEMS) systems due to their large piezoelectric coefficients, dielectric constant, and excellent electromechanical properties [1-2]. Since the piezoelectric properties of PZT thin films are influenced by the mechanical coefficients, designing MEMS devices should understand the scaling effects of mechanical properties of PZT thin films. In recent years, much attention has been paid to the measurement of the mechanical properties of PZT thin films. Wang et al. [3] studied the crystalline orientation dependence on the mechanical properties of PZT thin films. Delobelle et al. [4-5] measured the mechanical properties of PZT films employing different electrode materials. Fang et al. [6] investigated the influence of annealing temperature on the nanomechanical properties of PZT thin film. Xu et al. [7] and Bahr et al. [8] studied the mechanical properties of PZT thin film by nanoindentation. C.Chima-Okereke et al.[9] also investigated the mechanical properties of PZT multilayer systems by experimental ,analytical and FEA method between which good agreement was shown, and pointed out the mechanical properties of surface film can be measured in certain range of the a/t (contact radius/film thickness) value .However, a study about the effects of substrates on the mechanical properties of PZT films has not been undertaken. Since the mechanical properties of PZT thin films are often dominated by other layer structures such as substrates, this study conducted an investigation into the effects of different substrates and the crystalline orientations on the nanomechanical properties of PZT thin films. Compared with other methods of exploring the mechanical properties of thin f
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