Downscaling of Pb(Zr,Ti)O-3 film thickness for low-voltage ferroelectric capacitors: Effect of charge relaxation at the interfaces

In this communication we address two issues essential for low-voltage memor y applications of ferroelectric thin films: the size effect on polarization switching, and polarization fatigue. According to the proposed concept, bo th of these phenomena are controlled by local injection of charge into the interfacial layers of the ferroelectric film. In the experimental part of t his work, we show that the entrapped charge relaxation can be enhanced by i ntroducing a thin RuO2 layer into the top interface of the Pt/PZT/Pt ferroe lectric capacitor. Capacitors prepared in this way using PZT with a 45/55 Z r/Ti ratio show a substantial improvement of fatigue performance and withst and relatively well the thickness downscaling. As a result, these capacitor s exhibited good ferroelectric properties for driving voltage amplitudes as low as 0.6-0.8 V. Our results suggest that control of charge relaxation at the interface is a key issue for development of low-voltage ferroelectric capacitors. (C) 2000 American Institute of Physics. [S0021-8979(00)04016-0] .