Nonlinear Dielectric Spectroscopy of P(VDF-TrFE-CFE) Films for Non-Volatile Memory Applications

The potential suitability of P(VDF-TrFE-CFE) relaxor-ferroelectric terpolymer films for non-volatile memory devices is assessed from the $\varepsilon_{2}/(3\varepsilon_{0}^{2}\varepsilon_{1}^{3})$ ratio that is directly proportional to the remanent polarization. Non-linear dielectric spectroscopy was employed to obtain $\varepsilon_{2}/(3\varepsilon_{0}^{2}\varepsilon_{1}^{3})$ ratios vs. time or temperature. For comparison, dielectric hysteresis loops were measured in a Sawyer-Tower circuit. Optimum poling temperatures and polarization stabilities of non-annealed and annealed terpolymer samples were also determined. The results indicate that annealed samples show definite polarization values only when poled at low temperatures close to their respective glass transition. On the other hand, non-annealed samples allow poling at ambient temperature due to their higher content of the ferroelectric crystalline phase. Both, non-annealed and annealed terpolymer films show stable polarization values for several minutes after field removal – indicating their possible use at least in short-term memory devices.