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力显微镜(TRPFM)测试。我们发现，在300 mV/m以下，开关时间服从指数规律，并且在高场下转移到一个低功率。在800 mV/m时最快可达1 ns。由于电击穿和热扩散时间的原因，这一开关时间实际上是它的极限值。TR-PFM可以直接观察到由铁电聚合物薄膜组成的晶体颗粒中发生的假想成核-生长过程。分别测定了成核几率和生长速度，它们的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.