Unipolar polarization switching and high-endurance memory operation of HZO/Si anti-ferroelectric FETs

We experimentally demonstrate the anti-ferroelectric (AFE) behavior of a Hf1−x Zr x O2 (HZO)/Si FET and its potential for high-endurance nonvolatile memory operation. The AFE-HZO FET with Zr content of 75% exhibits a double polarization switching and half-loop switching of its double hysteresis under bipolar and unipolar bias conditions, respectively. The counterclockwise hysteresis in the transfer I d–V g characteristics is demonstrated under unipolar V g sweep through half-loop polarization in AFeFET. The steep subthreshold swing values were observed for both forward and backward V g sweeps of I d–V g curves for AFeFET under unipolar bias condition. The nonvolatile feature of AFeFET is achieved by introducing the optimized hold voltage of 1.3 V during the retention period. The threshold voltage shift can be realized by utilizing the unipolar program/erase V g pulses. Also, the high-endurance properties of HZO/Si AFeFET are demonstrated under unipolar V g stress with observable memory window up to 109 cycles without gate insulator breakdown.