Mechanical and Ferroelectric Response of Highly Textured PZT Films for Low Power MEMS
Technical Report,01 Jun 2012,31 May 2016
University of Illinois - Urbana - Champaign Champaign United States
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This program investigated the elastic and inelastic behavior of textured Pt and PZT thin films integrated in PZT-based MEMS. The effect of film thickness and grain size on the mechanical response of freestanding nanocrystalline 111-textured Pt films, with thicknesses in the range of 100 to 1000 nm, was experimentally and analytically investigated. The measured elastic modulus of Pt 1672 GPa agreed well with theoretical estimates for 111-textured polycrystalline Pt. The experimentally determined proportional limit was consistent with predictions by a modified Thompson model for plastic deformation of polycrystalline columnar metal films, while a Taylor strain hardening model was superimposed to the modified Thompson model to account for additional hardening due to dislocation interactions. The effect of texture on the open-circuit mechanical response and piezoelectric properties of 500-nm thick freestanding PZT films was also investigated. The open circuit modulus varied linearly between 902 GPa for 001 texture and 1223 GPa for 111 texture. 001 texture resulted in the most pronounced non-linear stress-strain response indicating easier 90 domain switching. The piezoelectric properties depended strongly on the PZT film texture PZT films with high 001 texture content demonstrated much more pronounced piezoelectric response than those with high 111 texture content.
- Electricity and Magnetism
- Electrical and Electronic Equipment