Ferroelectricity and the phase transition in large area evaporated vinylidene fluoride oligomer thin films

Authors

Keith Foreman, University of Nebraska-LincolnFollow
Shashi Poddar, University of Nebraska-LincolnFollow
Stephen Ducharme, University of Nebraska - LincolnFollow
Shireen Adenwalla, University of Nebraska - LincolnFollow

Date of this Version

2017

Citation

JOURNAL OF APPLIED PHYSICS 121, 194103 (2017)

http://dx.doi.org/10.1063/1.4983820

Comments

Published by AIP Publishing. Used by permission

Abstract

Organic ferroelectric materials, including the well-known poly(vinylidene fluoride) and its copolymers, have been extensively studied and used for a variety of applications. In contrast, the VDF oligomer has not been thoroughly investigated and is not widely used, if used at all. One key advantage the oligomer has over the polymer is that it can be thermally evaporated in vacuum, allowing for the growth of complex heterostructures while maintaining interfacial cleanliness. Here, we report on the ferroelectric properties of high-quality VDF oligomer thin films over relatively large areas on the order of mm². The operating temperature is identified via differential scanning calorimetry and pyroelectric measurements. Pyroelectric measurements also reveal a stable remanent polarization for these films which persists over very long time scales, an important result for nonvolatile data storage. Temperature dependent pyroelectric and capacitance measurements provide compelling evidence for the phase transition in these films. Capacitance-voltage and currentvoltage measurements are used to confirm ferroelectricity, quantify the dielectric loss, and calculate the spontaneous polarization. Finally, piezoresponse force microscopy is used to demonstrate large area, low-voltage ferroelectric domain reading/writing in VDF oligomer thin films. This work enables new channels for VDF oligomer applications and research.