Dependence of threshold thickness of crystallization and film morphology on film processing conditions in poly(vinylidene fluoride-trifluoroethylene) copolymer thin films
Dependence of threshold thickness of crystallization and film morphology on film processing conditions in poly(vinylidene fluoride-trifluoroethylene) copolymer thin films
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DOI：
10.1063/1.1503395
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发表时间：
2002-08
影响因子：
3.2
通讯作者：
F. Xia;B. Razavi;Haisheng Xu;Z.Y. Cheng;Qiming Zhang
中科院分区：
文献类型：
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作者：
F. Xia;B. Razavi;Haisheng Xu;Z.Y. Cheng;Qiming Zhang
聚偏氟乙烯-三氟乙烯在金属化硅衬底上的旋转流延薄膜中，存在一个结晶阈值厚度dth，低于此厚度结晶度急剧下降。由于聚合物的结晶度和功能性质之间的直接联系，薄膜的铁电性质，包括介电常数，极化水平和极化切换速度，有一个相应的大的变化，作为厚度减少到dth以下。详细的微观结构研究表明，该阈值厚度是由稳定的晶体片层尺寸沿着膜厚方向。通过改变膜处理条件以减小厚度方向上的晶体片层尺寸，可以显著减小dth。结果表明，在SiO2薄膜中获得了较好的铁电响应。
In spin-cast films of poly(vinylidene fluoride–trifluoroethylene) on metalized silicon substrate, there exists a threshold thickness of crystallization dth, below which the crystallinity drops precipitously. Due to the direct link between the crystallinity and functional properties in the polymer, there is a corresponding large change in the film ferroelectric properties, including the dielectric constant, the polarization level, and polarization switching speed, as the thickness is reduced to below dth. Detail microstructure studies show that this threshold thickness is controlled by the stable crystal lamellar size along the film thickness direction. By varying the film processing condition to reduce the crystal lamellar size in the thickness direction, dth can be reduced markedly. As a result, better ferroelectric responses were obtained in ultrathin films.