Study Of Characteristics Of Organic Ferroelectric Memory Devices

Organic ferroelectric materials PVDF and its copolymers P (VDF-TrFE) has draw a great attention recently. It resolved the interface problems that long-standing in inorganic ferroelectric material memories, and overcomes the process problems exist in the inorganic semiconductor industry, which greatly simplified the process steps. Organic field-effect transistors (FeFETs) based on organic ferroelectrics have a non-destructive readout, strong data retention capability, small size, can be repeatedly erased, low operating voltage and short programming time, etc. In addition, the memory devices also can be used in the simple circuit of the flexible substrate, RFID tags, and they have a good prospect.The purpose of this thesis is to explore the memory characteristics of organic ferroelectric materials, for the request of give some useful guidance to experimental work. The main work is divided into three parts:1. Establishment of a polarization model for the polarization characteristics of organic ferroelectric materials, and verified the applicability of the model by comparing the numerical results and experimental data.2. Based on the polarize model, we analyzed the metal-organic ferroelectric thin films-metal (MFM) capacitor structure. And combined with the effective transport hopping energy model as well as the Poole-Frenkel mobility model in organic semiconductors, we obtained the memory characteristics of metal-organic ferroelectric thin films-semiconductor (MFS) heterostructure and FeFET. By using the aluminum electrode, the memory window of MFM structure capacitance and MFS heterostructures increases, but the switch ratio of FeFET reduced. Organic semiconductor in the inversion state is not suitable for FeFETs memory application.3. We discussed the polarization characteristics of the copolymer P(VDF-TrFE) with different solution ratio, and deduced the memory characterize of MFM capacitor, MFS hererostructure as well as FeFET. Then we get the rules of the memory characterize dependence of the proportion of VDF in P(VDF-TrFE).Organic ferroelectric materials show a good characteristic of polarization, so that the organic ferroelectric memory devices have a well memory characteristic.