Abstract
Solution-deposited ferroelectric films often are under mechanical stress due to the difference in thermal expansion coefficients between films and substrate materials. Knowledge of how stress changes the ferroelectric response under different actuation conditions is essential when selecting a substrate for film deposition. Here, a comparative study of the ferroelectric properties of lead zirconate titanate thin films on transparent fused silica glass and sapphire substrates is presented. Sapphire exerts a compressive in-plane stress on the film, favoring an out-of-plane domain orientation, while fused silica causes tensile in-plane stress and a predominantly in-plane domain configuration. As expected, the out-of-plane polarization is high under in-plane compressive stress but reduced by a factor of nearly 4 by in-plane tensile stress. In contrast, the in-plane polarization shows an unexpectedly weak stress dependence. It is larger by only about 10% under tensile stress compared to compressive stress. Permittivity increases when the major domain orientation does not coincide with the electric field. The observations are explained based on a model taking into account the crystallographic structure of the film.
Highlights
When designing ferroelectric thin film devices for optimum performance, both substrate choice and electrode design are critical factors
The out-of-plane polarization is high under in-plane compressive stress but reduced by a factor of nearly 4 by in-plane tensile stress
In the case of the MIM configuration, the field is strictly perpendicular to the film plane; for the interdigitated electrodes (IDEs), it is mainly parallel to the direction film plane with a slight curvature
Summary
When designing ferroelectric thin film devices for optimum performance, both substrate choice and electrode design are critical factors. The most typical design, e.g., for piezoelectric actuators or ferroelectric random access memories (RAMs), is a metal–insulator–metal (MIM) geometry with the film sandwiched between a top and bottom electrode. Coplanar electrode configurations can be, e.g., interdigitated electrodes (IDEs) or concentric ring designs.. Coplanar electrode configurations can be, e.g., interdigitated electrodes (IDEs) or concentric ring designs.2,3 They are used for surface acoustic wave filters, sensors, actuators, energy harvesters, or haptic feedback devices.. Applications based on optical transparency typically require both a transparent substrate and the absence of metallic MIM electrodes and have to rely on IDEs. In addition, applications based on optical transparency typically require both a transparent substrate and the absence of metallic MIM electrodes and have to rely on IDEs Both MIM and IDE designs are schematically depicted, along with the electric field direction for each structure. In the case of the MIM configuration, the field is strictly perpendicular to the film plane; for the IDE, it is mainly parallel to the direction film plane with a slight curvature.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
