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Study of rewritable thin-film memories using ferroelectric polymers

使用铁电聚合物可重写薄膜存储器的研究

基本信息

批准号：
12650875
负责人：
IKEDA Susumu
金额：
$ 2.11万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650875/
关键词：
ferroelectric polymer thin film memory VDF TrFE copolymer polymer dispersed liquid crystal nematic liquid crystal 5CB polarization internal field optical transmittance 高分子分散型液晶有機薄膜メモリー読み取り動作初期化

项目摘要

1. Ultra thin films of ferroelectric VDF/TrFE(vinylidene fluoride/ trifluoroethylene) copolymers were produced by use of spin-coating technique. We took aim at forming of submicron films whose polarization can be controlled by voltages less than about 10 V. The best condition for solvent, solution density and rate of rotation of spin coater was chosen by many tests. As the result, a thin film of 220 nm in thickness which exhibits a ferroelectric D-E hysteresis was obtained. This film can be used as a memory in an integral circuit. However, films of higher quality including higher ordered crystals are required to make a real memory, because the polarization reversal switching process observed in the submicron films described above is not so clear in comparison with those observed in films with the thickness more than 1μm.2. Memories have three elementary actions of writing, reading and initializing. About reading, we studied whether the change in the optical transmittance of the sample films can be used for the switching process of memories or not, in order to use them as the memory for optical circuit. We took up PDLC (polymer dispersed liquid crystal) composed of VDF/TrFE copolymer and nematic liquid crystal 5CB as a sample. The polarization of P(VDF/TrFE) was oriented by applying an external electric field to PDLC. The internal electric field originating from the ferroelectric polarization affected molecular orientation of the liquid crystal 5CB and changed the optical transmittance of PDLC. This result suggests that the changes in the optical transmittance can be used for the reading mechanism of the PDLC memory.From these results we conclude that the organic thin-film memory can be obtained using the ferroelectric properties of polymers.

1.采用旋涂法制备了VDF/TrFE（偏氟乙烯/三氟乙烯）共聚物铁电薄膜。我们的目标是形成亚微米薄膜，其极化可以控制的电压小于10 V左右。通过大量的试验，选择了最佳的溶剂，溶液浓度和旋转涂布机的转速条件。结果，获得了厚度为220 nm的薄膜，其表现出铁电D-E滞后。这种薄膜可用作集成电路中的存储器。然而，需要包括更高有序晶体的更高质量的膜来制造真实的存储器，因为在上述亚微米膜中观察到的极化反转转换过程与在厚度大于1μ m的膜中观察到的极化反转转换过程相比不那么清楚。记忆有三个基本动作：写、阅读和初始化。在阅读方面，我们研究了样品薄膜的透光率变化是否可以用于存储器的开关过程，以便将其用作光路存储器。以VDF/TrFE共聚物和5CB液晶组成的聚合物分散液晶（PDLC）为样品。P（VDF/TrFE）的极化取向是通过向PDLC施加外电场来实现的。由铁电极化产生的内电场影响液晶5CB的分子取向，改变PDLC的透光率。这一结果表明，光透射率的变化可以用于PDLC存储器的阅读机制。从这些结果，我们得出结论，有机薄膜存储器可以利用聚合物的铁电性能。