Dynamic dielectric-constant enhancement in Hf 1− x Zr x O 2 high- k dielectrics revealed by fast C – V measurement

Abstract Ferroelectric Hf 1− x Zr x O 2 (HZO) is a promising high- k material for electron devices that requires high capacitance as it possesses a higher dielectric constant ( k -value). The capacitance–voltage ( C – V ) characteristics of HZO-based materials have been widely investigated near the quasi-static condition, while the behavior at high frequencies, where the ferroelectric polarization is likely to be a transient state, has not been understood well. In this study, we develop a fast C – V measurement method to evaluate the C – V characteristics of Hf 0.5 Zr 0.5 O 2 films with various voltage sweep speeds, up to 400 V s −1 . The k -value of our 5.5 nm thick HZO extracted from the fast C – V measurement exhibits an enhancement at higher voltage sweep speed at the rate of 1.94 per decade of sweep speed, reaching k -value of 55.7 at the sweep speed of 400 V s −1 , as compared to 50.0 at 0.4 V s −1 . We attribute this phenomenon to the relaxation response of polarization to the abrupt change in the electric field. This finding reveals that the dielectric constant of high- k HZO films is governed by polarization dynamics, enabling a dynamically enhanced dielectric response under high frequency operation.