Ferroelectric Capacitor

Ferroelectric Capacitor Fabrication and Characterization

A side project was learning how to improve the quality of the ferroelectric thin films we fabricated in our lab using poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Samples were fabricated with the following structure to avoid edge affects:

Ferroelectric capacitor structure visualization. The SiO2 wafer substrate is shown in dark grey, with a bottom electrode formed by a thin films of Cu (orange) capped by an Al thin film (light grey) partially covering the substrate. The ferroelectric layer is shown in clear, with the PVDF-HFP polymer chains oriented on the substrate . The top electrode is another Al thin film (light grey) wih a thicker thin film of Au (yellow).

The differences in samples between those fabricated manually and those from an automated system are visible to the eye.

(LEFT) A PVDF-HFP thin film on SiO2 formed by manual Langmuir Blodgett deposition. (RIGHT) A PVDF-HFP thin film formed by automated Langmuir Blodgett deposition. A slight irridescence is visible; always a good sign.

A simple Sawyer-Tower circuit can do the trick for hysteresis measurements, but we used Radiant Ferroelectric tester to evaluate the improvement in thin film quality

(LEFT) Hysteresis characterization of a PVDF-HFP thin film formed by manual Langmuir Blodgett deposition. (RIGHT) Hysteresis characterization of a PVDF-HFP thin film formed by automated Langmuir Blodgett deposition.

[1]Dale, A. S. (2020). Developing an Approach to Improve Beta-Phase Properties in Ferroelectric PVDF-HFP Thin Films. Purdue University.

[2]Mosey, A., Dale, A. S., Hao, G., N’Diaye, A., Dowben, P. A., & Cheng, R. (2020). Quantitative study of the energy changes in voltage-controlled spin crossover molecular thin films. The Journal of Physical Chemistry Letters, 11(19), 8231-8237.