A Study of Ferroelectric Polarization Switching and Negative Capacitance Effect for Enhanced Energy Storage in on-Chip Electrostatic Supercapacitors

In this work, we propose an experimental study aimed at understanding fundamental effects and optimizing energy storage density and efficiency of on-chip ferroelectric electrostatic supercapacitors based on doped high-k dielectrics. In our experimental test vehicles based on nanometer-thin stacks of Si:HfO 2 and Al 2 O 3 , we obtain efficiencies up to 90% with energy storage density 90 J/cm ³ . We demonstrate for the first time that in such ferroelectric stacks, negative capacitance and dipole switching can both contribute to energy density enhancement, with an enhancement of up to 40% when the negative capacitance regime is exploited. Furthermore, we show that charging in current mode such ferroelectric supercapacitors could be more efficient for the wake-up of ferroelectric effects for energy storage. This paves the way for future implementations of on-chip energy storage by properly designing the ferroelectric stacks and their operation in the right regime of such unique rechargeable energy storage devices.