Studies on unltra-fast polarization switching in ferroelectric polymer thin films by means of time-resolved piezo-force-microscopy

对偏氟乙烯基铁电聚合物薄膜进行了超快极化开关和时间分辨压电显微镜（TR-PFM）测量。我们发现开关时间在300MV/m以下遵循指数规律，并在高场下转换为低功率。在800MV/m的速度下，速度达到1ns。由于电击穿和热扩散时间的限制，该开关时间实际上是有限的。TR-PFM允许直接观察假想的成核生长过程发生在包含铁电聚合物薄膜的晶体颗粒中。分别测定了成核概率和生长速度，其值与观察到的铁电开关时间一致。

Measurements of ultrafast polarization switching and time-resolved piezo-force microscopy (TR-PFM) were conducted for thin films of vinylidene fluoride-based ferroelectric polymers. We found that the switching time follows an exponential law below 300MV/m and is transferred to a power low at higher fields. It becomes as fast as 1 ns at 800MV/m. This switching time is its practically limited value due to electrical breakdown and thermal diffusion time. TR-PFM allowed for direct observation of hypothetical nucleation-growth processes taking place in crystalline grains comprising ferroelectric polymer thin films. The nucleation probability and growth velocity were separately determined and their values were shown to be consistent with observed ferroelectric switching time.