Applications Of Ferroelectric Polymers To New Memories

The spontaneous polarization is one of the most important features of ferroelectric polymers.It can be regulated by the applied fields,which change spontaneous polarization direction and level.This feature has attracted much attention in the field of flexible electronics.This thesis concentrates on the new applications of the ferroelectric polymers in the memories.Different from the Ferroelectric Random Access Memories,the two memories in this thesis store information based on the level of the polarization.The main research contents are as follows:1?The phase change memory has become a new hot spot in the field of memory for its fast read speed and huge cycle times.Here we use ferroelectric-paraelectric transition in crystalline phase of ferroelectric polymers to store information.As organic materials,ferroelectric polymers meet well the requirements of flexible electronics.Moreover,its phase transition temperature is considerably lower than the traditional phase change material,GST.With these two features,ferroelectric polymers can be fabricated to flexible memory with low operating temperature and high density of data storage.We choose ferroelectric terpolymer as the phase change material instead of copolymers for nonvolatile property.The phase transition of the terpolymer is a continuous process around the phase transition temperature,therefore it is suitable for the multi-bit memory.2?Memristor is found by Hewlett Packard in 2008.Since its birthday,it has shown the properties of huge data storage density and strong ability of logical operation when it combines with crossbar latch.We fabricate the light-induced memristor from the composites of ferroelectric polymers and semiconductors.The current of the device strongly dependents on the luminous flux.We study the effects of the two components in the composites on the performance of the device.We also make the light-induced memristor device,which may carry out simple addition and subtraction operations with lights.Here we choose the ferroelectric copolymers with strong polarization,since the device can response to light faster and show larger ON/OFF ratio than the terpolymer.