Negative capacitance in ferroelectric materials and its potential use for transistors with <60 mV/decade subthreshold swing

Abstract

Owing to the energy barrier that forms during phase transition and separates the two degenerate polarization states, a ferroelectric material could show negative differential capacitance while in non-equilibrium. The state of negative capacitance is unstable, but just as a series resistance can stabilize the negative differential resistance of an Esaki diode, it is also possible to stabilize a ferroelectric in the negative differential capacitance state by placing a series dielectric capacitor. In this configuration, the ferroelectric acts as a `transformer' that boosts up the input voltage. The resulting amplification could lower the voltage needed to operate a transistor below the limit otherwise imposed by the Boltzmann distribution of electrons.