Characteristics of Al/SrBi2Ta2O9/HfO2/Si structure using HfO2 as buffer layer for ferro electric-gate field effect transistors

We have investigated the structural and electrical properties of metal-ferroelectric-insulator-semiconductor capacitors with 280-nm-thick SrBi2Ta2O9 (SBT) ferroelectric films grown on Si as well as on Si with buffer layer (HfO2). The SBT thin films and HfO2 buffer layer were fabricated using rf magnetron sputtering method. XRD patterns revealed the formation of well crystallized SBT perovskite thin film on the HfO2 buffer layer which is evident from sharp peaks in XRD spectra. The electrical properties of I the metal-ferroelectric-insulator-semiconductor (MFIS) structure were characterized by varying thickness of the HfO2 layer. The width of memory window in the capacitance-voltage curves for the MFIS structure decreased with increasing thickness of HfO2 layer. Leakage current density decreased significantly after inserting HfO2 buffer layer. This shows that the proposed Al/SrBi2Ta2O9/HfO2/Si structure ideally suitable for high performance ferroelectric memories.