Impact of HfTaO Buffer Layer on Data Retention Characteristics of Ferroelectric-Gate FET for Nonvolatile Memory Applications

A p-channel metal-ferroelectric-insulator-silicon field-effect transistor (FET) with a 300-nm-thick SrBi2Ta2O9(SBT) ferroelectric film and a 10-nm-thick HfTaO layer on silicon substrate was fabricated and characterized. The device shows a nearly unchanged memory window of about 0.9 V after a 2 × 1011-cycles fatigue test, an on/off current ratio of more than 107, and a field-effect mobility of approximately 42 cm2/V · s. Moreover, a drain-current on/off ratio as high as 105was obtained with a fixed gate voltage of 2.5 V after over a 105-s elapsed time without any obvious degradation. These results may suggest that the Pt/SBT/HfTaO/Si FET is suitable for high-performance ferroelectric memory.