In this study, an experimental study of negative capacitance is performed in order to overcome the physical limit of subthreshold slope (SS), SS >= 60 mV/decade at 300 K, which is originated from (i) using the thermionic emission process in complementary metal-oxide-semiconductor (CMOS) technology and (ii) non-scalability of the thermal voltage k(B)T/q (i.e., in order to realize SS lower than 60 mV/decade at 300 K). To make the surface potential higher than the gate voltage, a step-up voltage amplifier is included in the CMOS gate stack using a ferroelectric capacitor implemented with ferroelectric material. The measured SS in long-channel CMOS transistors is 13 mV per decade at 300 K. A simple connection of the ferroelectric capacitor to a complementary metal oxide semiconductor (CMOS) gate electrode would provide a new evolutionary pathway for future CMOS scaling. (C) 2015 Elsevier B.V. All rights reserved.