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Lead zirconate titanate (PZT) thin films offer advantages in microelectromechanical systems (MEMSs) including large motion, lower drive voltage, and high energy densities. Depending on the application, different substrates are sometimes required. Self-heating occurs in the PZT MEMS due to the energy loss from domain wall motion, which can degrade the device performance and reliability. In this work, the self-heating of PZT thin films on Si and glass and a film released from a substrate were investigated to understand the effect of substrates on the device temperature rise. Nano-particle assisted Raman thermometry was employed to quantify the operational temperature rise of these PZT actuators. The results were validated using a finite element thermal model, where the volumetric heat generation was experimentally determined from the hysteresis loss. While the volumetric heat generation of the PZT films on different substrates was similar, the PZT films on the Si substrate showed a minimal temperature rise due to the effective heat dissipation through the high thermal conductivity substrate. The temperature rise on the released structure is 6.8× higher than that on the glass substrates due to the absence of vertical heat dissipation. The experimental and modeling results show that the thin layer of residual Si remaining after etching plays a crucial role in mitigating the effect of device self-heating. The outcomes of this study suggest that high thermal conductivity passive elastic layers can be used as an effective thermal management solution for PZT-based MEMS actuators.
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Substrate effects in hysteresis of microscale Ni–Mn–Sn Heusler alloy films
During martensitic phase transformations in thin films, substrates impact hysteresis by introducing an additional interface, which can inhibit martensite/austenite interface motion. In order to reduce hysteresis, we examine 2.9–14.5 μm thick Ni–Mn–Sn films, which in some cases have been delaminated from the substrates before or after annealing. We compare thermal hysteresis and defect densities at the interface. Delaminating films prior to annealing decreases hysteresis, whereas delaminating films after annealing does not significantly impact hysteresis. Substrate effects are attributed to the thermal expansion mismatch between the film and substrate, resulting in the formation of dislocations at the interface and, consequentially, an increase in frictional resistance to martensite/austenite interface motion.
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- Award ID(s):
- 1847956
- PAR ID:
- 10572240
- Publisher / Repository:
- AIP (American Institute of Physics)
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 123
- Issue:
- 7
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0159129
