The ferroelectricity and electrical properties of P(VDF-TrFE) copolymer film

Poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) copolymer thin films with a molar ratio of 75/25 have been studied to investigate their ferroelectricity. P(VDF-TrFE) solutions of 3, 7 and 10 wt% were fabricated on Si(100) substrates by using a spin-coating method. In order to achieve crystallization, we annealed the deposited films at 150°C for one and half hours without any addional treatments, such as a heat-treatment, poling, or mechanical drawing. The thicknesses of the deposited films were 60, 170 and 400 nm for the 3, 7 and 10 wt% solutions, respectively. Hysteretic characteristics were observed in the capacitance-voltage (C-V) curves for Au/P (VDF-TrFE)/Si diodes and may be considered to be due to the ferroelectric nature of the P(VDF-TrFE) films. The memory window width was measured at a low voltage below 1 V for a film coated with a 3 wt% solution. The memory window widths in this metal-ferroelectric-semiconductor (MFS) fabricated with 3, 7 and 10 wt% P(VDF-TrFE) solutions were about 1.2, 2.7 and 3.6 V for a bias sweep from -5 V to 5 V, respectively.