Switching kinetics of lead zirconate titanate sub-micron thin-film memories

Abstract

We have determined the coercive voltage E_c as a function of thickness d for PZT ferroelectric memories. For thick films (≫ 1μm), E_c ∼ d^−1/3 , in accord with the theory of Kay and Dunn [Phil Mag. 7, 2027 (1962)]; for submicron films, E_c ∼ d^−4/3 , in accord with Neel's theory for coercive magnetic field H_c in thin magnetic films [J. Phys Radium 17, 250 (1956)]. The switching times and shape i(t) of the displacement current transient were measured vs. temperature and field. They satisfy the theory of Ishibashi and Takagi [J. Phys. Soc. Jpn. 31, 506 (1971)] and show that domain nucleation is approximately two dimensional. The times τ are very fast (≪100ns at 1.0V drive) and depend upon field E and reduced temperature t = (T_c - T)/T_C according to a scaled relationship {Orihara and Ishibashi [Jpn. J. Appl. Phys. 24, 902 (1985)]}

where x is given by t/E and α is an activation field equivalent to 120 kV/cm at 300K.