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.采用旋涂技术制备了铁电VDF/TrFE（偏二氟乙烯/三氟乙烯）共聚物超薄膜，我们的目标是形成可以通过小于约10V的电压控制极化的亚微米薄膜。通过多次试验选择了溶剂、溶液密度和旋涂机转速的条件，结果形成了具有铁电性的厚度为220 nm的薄膜。获得了 D-E 磁滞现象，该薄膜可用作集成电路中的存储器，但是，需要包含更高有序晶体的更高质量的薄膜，因为在上述亚微米薄膜中观察到的极化反转转换过程是不稳定的。与厚度大于1μm的薄膜中观察到的情况相比，不太明显。2．存储器具有写入、读取和初始化三个基本动作。关于读取，我们研究了样品薄膜的光学透过率的变化。为了将它们用作光电路的存储器，我们采用了由VDF/TrFE共聚物和向列液晶5CB组成的PDLC（聚合物分散液晶）作为样品。 P(VDF/TrFE)通过向PDLC施加外部电场而取向，源自铁电极化的内部电场影响液晶5CB的分子取向并改变液晶5CB的光学透射率。 PDLC。这个结果表明光学透射率的变化可以用于PDLC存储器的读取机制。从这些结果我们得出结论，可以利用聚合物的铁电特性来获得有机薄膜存储器。