Evidence for forward domain growth being rate-limiting step in polarization switching in < 111 >-oriented-Pb(Zr0.45Ti0.55)O-3 thin-film capacitors

Abstract

We studied polarization switching of 295 nm thick <111>-oriented-Pb(Zr0.45Ti0.55)O-3 (PZT) thin-film capacitors through a polarization hysteresis loop and piezoelectric force microscopy (PFM) on top of the Pt electrode. Positive voltage pulses of 450 kV/cm and 2.5 ms were applied to the top as a poling pulse. Negative pulses ranging from -45 to -60 kV/cm at an interval of 3 kV/cm were applied to the top electrode. After each pulse, we performed PFM imaging by applying 17 kHz ac voltage of 1 V peak to peak to the bottom electrode while grounding the top one and the tip. The first-harmonic amplitude and phase of the tip vibration signal were mapped over the scanned area of 10x10 mum(2). Subsequently, we measured the polarization hysteresis curve at 100 Hz after each domain image acquisition to estimate the volume fraction of switched polarization induced by the positive voltage pulses. We analyzed the areal fraction of switched domains as a function of pulse voltage from phase images and compared it with the volume fraction obtained from the hysteresis loops. Based on the evolution of domain images and the comparison plots of the areal and volume fractions of switched domains, we conclude that forward domain growth is a rate-limiting step during polarization reversal in <111>-oriented-PZT thin-film capacitors. (C) 2002 American Institute of Physics.