Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Sep;56(9):1861-7. doi: 10.1109/TUFFC.2009.1262.
Thin-film ferroelectric capacitance can be obtained by 2 different methods. Capacitance obtained using the derivative of its hysteresis loop is related to large applied signals and can be called the large-signal capacitance. Capacitance measured directly with a small, applied ac signal together with a slow changing dc bias is called the small-signal capacitance. This paper investigated the voltage dependence of the large- and small-signal capacitances. Measurements show that the large-signal C-V curve of thin-film ferroelectrics has much sharper peaks and higher peak values than the small-signal C-V curve. Analyses based on the Landau-Khalatnikov model shows that practical small-signal capacitance is closer to the ideal capacitance. However, its C-V curve has clearance areas around the coercive voltage, and the polarization switching is not reflected in the small-signal capacitance. This causes the peaks of small-signal C-V curves to be lower than that of large-signal C-V curves.
可以通过两种不同的方法获得薄膜铁电电容。通过其滞后回线的导数获得的电容与大的应用信号有关，可以称为大信号电容。通过施加小的交流信号和缓慢变化的直流偏置直接测量的电容称为小信号电容。本文研究了大信号和小信号电容的电压依赖性。测量表明，薄膜铁电体的大信号 C-V 曲线具有比小信号 C-V 曲线更尖锐的峰和更高的峰值。基于朗道-卡哈林科夫模型的分析表明，实际的小信号电容更接近理想电容。然而，它的 C-V 曲线在矫顽电压周围有间隙区域，并且极化切换不会反映在小信号电容中。这导致小信号 C-V 曲线的峰值低于大信号 C-V 曲线的峰值。
