Quantifying the Role of Electronic Charge Trap States on Imprint Behavior in Ferroelectric Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) Thin Films

ABSTRACTPoly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric thin films are a potentially promising material for sensors or non-volatile memories. Imprint, the time-dependent resistance to polarization reversal, is a key material property that limits applications and is poorly understood. Based on experimental time and temperature dependences, we propose and investigate the link between imprint and charge trap states. A novel fast-ramp thermally stimulated current (TSC) measurement was developed to quantify and characterize the traps in an appropriate time-frame.Thin films of P(VDF-TrFE) on oxidized Si substrates were characterized following controlled initialization, fatigue, polarization, and imprint. Trap states were thermally filled/emptied by temperature cycling between 20–100 °C, using heating and cooling rates between 1 and 5 °C/s. Dynamics of this fast-ramp TSC indicate the presence of not only trap states, but also reversible and non-reversible charge accumulation. The presence of electrically active traps were verified by measurements over 1–10 s imprint times. Trapped charge directly correlated with the log of the imprint time, with a rate of ∼0.12 /μC/cm2/decade.