Research On High Performance Flexible Ferroelectric Organic Field-effect Transistor Nonvolatile Memory

The information industry is the pillar industry of the national economy development in our country,among which the nonvolatile storage is the core part.Ferroelectric type organic transistor non-volatile memory(FE-OFET-NVM)possesses many advantages,such as non-destructive read,long-term data storage,fast responseability,flexible,simple process and low cost fabrication and is expected to become the next generation memory.It has broad application prospects in portable flash storage,integrated circuit,product labels,networking,flexible display.Ferroelectric polymer PVDF and its copolymer P(VDF-Tr FE)are the most commonly used gate dielectric materials for a FE-OFET-NVM.Over the past decade,researchers have made great progress in the performance of FE-OFET-NVM based on PVDF or P(VDF-Tr FE)by developing high performance organic semiconductors and processed technology.However,there are still two key problems that limit the application of this kind of devices in the industrialization,i.e.,high operating voltage(±20 V~±80V)and low field effect mobility(10-4~10-1 cm2/Vs).In this paper,we focus on the two key problems in FE-OFET-NVM and launch a series of researches:(1)First,the novel ferroelectric polymer P(VDF-TrFE-CTFE)was studied.The results show that it has high remanent polarization and low coercive field with 13.6 mC/m2 and 14.8 MV/m respectively.(2)Second,we constructed a Pentacene based FE-OFET-NVM using P(VDF-TrFE-CTFE)as the gate dielectric layer.A ferroelectric hysteresis behavior was observed with low operating voltage(±15 V)and mobility of 10-4 ~ 10-3 cm2/Vs.(3)Third,we employed an UVO treatment on P(VDF-Tr FE-CTFE)surface to change the Pentacene growth of stacking modes and improve the crystalline quality,which effectively enhance the mobility of FE-OFET-NVM,up to 0.8 cm2/Vs.(4)Fourth,we used AlOx as the passivation layer between P(VDF-TrFE-CTFE)and Pentacene film.As a result,it demonstrated to greatly improve the mobility of the device;The highest value was 9.3 cm2/Vs which is highest value reported up to date.(5)Fifth,the operating voltage of FE-OFET-NVM was further decreased by reducing the gate dielectric layer thickness and optimizing device structure.The optimized voltage is ±4 V,which is the lowest value reported up to data.(6)Finally,we successfully developed a high performance flexible FE-OFET-NVM with high mobility and low operating voltage.Meanwhile,and it exhibited excellent flexible mechanical durability.