title: Time-Dependent Negative Capacitance Effects in Al2O3/BaTiO3 Bilayers.
abstract: The negative capacitance (NC) effects in ferroelectric materials have emerged as the possible solution to low-power transistor devices and high-charge-density capacitors. Although the steep switching characteristic (subthreshold swing < sub-60 mV/dec) has been demonstrated in various devices combining the conventional transistors with ferroelectric gates, the actual applications of the NC effects are still some way off owing to the inherent hysteresis problem. This work reinterpreted the hysteretic properties of the NC effects within the time domain and demonstrated that capacitance (charge) boosting could be achieved without the hysteresis from the Al2O3/BaTiO3 bilayer capacitors through short-pulse charging. This work revealed that the hysteresis phenomenon in NC devices originated from the dielectric leakage of the dielectric layer. The suppression of charge injection via the dielectric leakage, which usually takes time, inhibits complete ferroelectric polarization switching during a short pulse time. It was demonstrated that a nonhysteretic NC effect can be achieved only within certain limited time and voltage ranges, but that these are sufficient for critical device applications.
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST) and JST, PRESTO , Higashi 1-1-1, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Taehwan
authors.initials: T
authors.lastname: Moon
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Kwon
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Cheol Hyun
authors.initials: CH
authors.lastname: An
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Han Joon
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Keum Do
authors.initials: KD
authors.lastname: Kim
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Seung Dam
authors.initials: SD
authors.lastname: Hyun
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Min Hyuk
authors.initials: MH
authors.lastname: Park
authors.affiliation: Department of Materials Science & Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Republic of Korea.
authors.forename: Cheol Seong
authors.initials: CS
authors.lastname: Hwang
keywords: Negative capacitance; charge injection; depolarization field; ferroelectrics thin films; hysteresis; low-power devices