Computation of the polarization due to the ferroelectric layer in a stacked capacitor from Sawyer-Tower hysteresis measurements

摘要

Reducing thickness of thin ferroelectric films typically comes with an apparent degradation of their dielectric and ferroelectric properties. In practice one observes a marked decrease of the linear dielectric constant and of remanent and maximum polarizations which may arise from the presence of passive layers at the film interfaces. We propose a numerical procedure which allows us to investigate the genuine behavior of switching domains in the ferroelectric layer of a stacked capacitor. This is achieved owing to the computation of the ferroelectric polarization from Sawyer-Tower hysteresis measurements. Moreover, the proposed procedure simultaneously allows us to remove the possible loop deformations through a numerical compensation acting as a modified Sawyer-Tower (ST) circuit. The method is based on a suitable formulation of the polarization taking place in the ferroelectric layer which corrects for both the passive layer effect and for the parasitics of the ST circuit. In addition, a fit procedure is described from which may be derived the linear dielectric constant of the ferroelectric layer, the resistivity, and the interfacial capacitance of the stacked capacitor.