Metal-ferroelectric-insulator-semiconductor memory FET with long retention and high endurance

A ferroelectric memory field-effect transistor (FET) with a Pt-SrBi₂Ta₂O₉-Hf-Al-O-Si gate stack was fabricated and its electrical properties were characterized. The insulating and ferroelectric layers were successively deposited by a laser ablation technique. Excellent data retention characteristics were obtained. The drain currents of on- and off-states were measured as a function of time, after ±6 V poling voltage applied to the gate electrode. The current ratio of the on- and off-states was more than 10⁶ even after 12 days. Moreover, after 10¹² cycles of ±8 V pulses, this ratio was also more than 10⁶.