Negative capacitance from the inductance of ferroelectric switching

Negative capacitance (NC) has been proposed to realize sub-Boltzmann steep-slope transistors in recent years. We provide experimental evidences and theoretical view for ferroelectric NC and inductance induced by polarization switching, based on an as-deposited nanoscale ferroelectric zirconium oxide (ZrO2) layer (nano-f-ZrO2). The experimental results are demonstrated in nano-f-ZrO2, including resistor–inductor–capacitor oscillations, positive reactance in Nyquist impedance plot, enhancement of capacitance, and sub-60 mV/dec subthreshold swing of nanoscale transistors. The theoretical analysis shows that ferroelectric polarization switching yields an effective electromotive force which is similar in behavior to Lenz’s law, leading to inductive and NC responses. Nano-beam electron diffraction reveals ferroelectric multi-domains in nano-f-ZrO2. Under small-signal operation, the switching of net polarization variation in ferroelectric multi-domains contributes to the ferroelectric inductance and NC. Nano-f-ZrO2 provides a pronounced inductance compared to conventional inductors, which would have impacts in a variety of applications including transistors, filters, oscillators, and radio-frequency-integrated circuits.