In this study, we investigated the molecular and microstructures of thin poly(vinylidene fluoride-chlorotrifluoro ethylene) (PVDF-CTFE) copolymer films with three different CTFE compositions of 10, 15, 20 wt% with respect to PVDF in relation with their ferroelectric properties. All PVDF-CTFE annealed at 130°C showed consecutive TTTT trans conformation with β type crystals while films molten and re-crystallized from a temperature above their melting points exhibited α type crystals with characteristic TGTG conformation. Microstructures of the films treated with the two different thermal histories also supported the formation of β and α type crystals with hundreds of nanometer scale sphere caps and micron level spherulites, respectively. Interestingly, PVDF-CTFE films with both α and β type crystals gave rise to relatively high remnant polarization of approximately 4 μC/cm 2 in metal/ferroelectric/metal capacitors regardless of the composition of CTFE. The ferroelectric polarization of a PVDF-CTFE film independent of thermal processing history allowed a wide processing window and easy fabrication protocol, resulting in a non-volatile ferroelectric field effect transistor memory which exhibited saturated hysteresis loops with the current ON/OFF ratio of approximately 103 at ±60 V sweep and reliable data retention.
Bibliographical noteFunding Information:
This work was supported by the Second Stage of the Brain Korea 21 Project in 2006 and by a National Research Foundation of Korea (NRF) Grant funded by the Ministry of Science and Technology (MEST), Republic of Korea (No. R11-2007-050-03001-0 ), ( MOEHRD ; KRF-2009-0080235 ). This research was also supported by the Converging Research Center Program through the Ministry of Education, Science and Technology (Nos. 2010K001430 and 2011K000685 ). The X-ray experiments at PAL (4C2 beamline), Korea were supported by MEST and POSCO, Korea.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Electrical and Electronic Engineering