Switching dynamics of si-doped hafnia-based ferroelectric FET across 11 orders of magnitude in time

Ferroelectricity (FE) in doped HfO₂, that was discovered a decade ago, enabled the integration of FE layers in a standard CMOS process. A FeFET is a field-effect transistor (FET) with an integrated FE layer in the gate-stack. The FeFET exhibits desired memory properties: non-volatility, low power, high-density, and CMOS-compatibility, which make it a promising candidate for non-volatile memory and neuromorphic applications. The shortest polarization time demonstrated to date in HfO₂-based FeFET was in the range of ~10 ns. Here, we report that a single sub-nanosecond pulse can fully switch HfO₂-based FeFETs and present the time-voltage switching kinetics from few seconds down to 300 ps - over 11 orders of magnitude in time.

We carried out measurements for an N-type FeFET device with a ~10 nm FE doped HfO₂ layer and channel dimensions of W=L=240 nm, fabricated in GlobalFoundries 28 nm bulk FeFET technology. Initially, we show that a single sub-ns pulse can fully switch the polarization in both polarities. To further investigate the switching kinetics in HfO₂-based FeFETs, we varied the applied write voltage amplitude and pulse width and extracted switching voltage vs duration in the range 300 ps to 8 s, more than 11 orders of magnitude in time. Our results show a remarkably steep time-voltage relation, which is captured by the classical nucleation theory across this wide range of pulse widths. These results are important for the progress of FeFET technology because they demonstrate the high-speed operation of the device, exhibiting sub-ns polarization switching at ~few volts amplitude while preserving long retention time at low voltage amplitude.