title: Negative Capacitance in Organic/Ferroelectric Capacitor to Implement Steep Switching MOS Devices.
abstract: Because of the "Boltzmann tyranny" (i.e., the nonscalability of thermal voltage), a certain minimum gate voltage in metal-oxide-semiconductor (MOS) devices is required for a 10-fold increase in drain-to-source current. The subthreshold slope (SS) in MOS devices is, at best, 60 mV/decade at 300 K. Negative capacitance in organic/ferroelectric materials is proposed in order to address this physical limitation in MOS technology. Here, we experimentally demonstrate the steep switching behavior of a MOS device-that is, SS ∼ 18 mV/decade (much less than 60 mV/decade) at 300 K-by taking advantage of negative capacitance in a MOS gate stack. This negative capacitance, originating from the dynamics of the stored energy in a phase transition of a ferroelectric material, can achieve the step-up conversion of internal voltage (i.e., internal voltage amplification in a MOS device). With the aid of a series-connected negative capacitor as an assistive device, the surface potential in the MOS device becomes higher than the applied gate voltage, so that a SS of 18 mV/decade at 300 K is reliably observed.
authors.affiliation: †School of Electrical and Computer Engineering, University of Seoul, Seoul 130-743, Republic of Korea.
authors.forename: Jaesung
authors.initials: J
authors.lastname: Jo
authors.affiliation: ‡Department of Electronic Engineering, Sogang University, Seoul 121-742, Republic of Korea.
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Choi
authors.affiliation: §Division of Electronics and Electrical Engineering, Dongguk University, Seoul 100-715, Republic of Korea.
authors.forename: Jung-Dong
authors.initials: JD
authors.lastname: Park
authors.affiliation: §Division of Electronics and Electrical Engineering, Dongguk University, Seoul 100-715, Republic of Korea.
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Shim
authors.affiliation: +School of Electrical Engineering, Korea University, Seoul 136-713, Republic of Korea.
authors.forename: Hyun-Yong
authors.initials: HY
authors.lastname: Yu
authors.affiliation: †School of Electrical and Computer Engineering, University of Seoul, Seoul 130-743, Republic of Korea.
authors.forename: Changhwan
authors.initials: C
authors.lastname: Shin
keywords: ferroelectrics; metal−oxide−semiconductor field-effect transistor (MOSFET); negative capacitance; steep switching