Triangular current: Method for measuring hysteresis loops of ferroelectric capacitors

Abstract

In this paper, we present a triangular current (TC) method for measuring the hysteresis loops of Pb(Zr,Ti)O-3 capacitors prepared on Pt/Ta/SiO2/Si substrates. Like the constant current (CC) method, this method is a current source mode method for obtaining hysteresis loops. By applying a triangular charging current to a specimen, a measured voltage profile, which is almost noiseless and smooth in the high-field region, is obtained and its hysteresis curve can be determined using integral calculus to convert the charging current to charge. Under various charging conditions, the similarity of the obtained hysteresis curves implies that the step charging current and number of steps do not affect the measured results. Moreover, the parasitic effect of the probe setup is found to possibly increase the maximum polarization of the ferroelectric capacitor as the area of the capacitor is reduced. The TC method can be utilized to determine the parasitic capacitance of the probe setup and then can easily determine the corrected hysteresis loops of small capacitors. These findings reveal that the TC method constitutes a new method for measuring the hysteresis loops of ferroelectric capacitors.