Enhanced memory window of Au/BaTiO3/SrTiO3/Si(001) MFIS structure with high c-axis orientation for non-volatile memory applications

Abstract

Metal–ferroelectric–insulator–semiconductor (MFIS) structures with BaTiO3 (BTO) as a ferroelectric film and SrTiO3 (STO) as an insulating buffer layer were fabricated on p-type Si(001) substrates using an ion beam sputter deposition technique. The effect of out-of-plane orientation on the electrical properties of the MFIS structures, including leakage current density and memory window behavior, were studied using the growth of the BTO ferroelectric film on Si substrate buffered by highly c-axis-oriented and random-oriented STO buffer layers. The experimental results show that the out-of-plane orientations of the BTO films were almost identical to those of the STO buffer layers. The MFIS structure with a high c-axis orientation exhibited a maximum clockwise capacitance-voltage memory window of 1.17 V with a low leakage current of 1.05×10−7 A/cm2 at an applied voltage of 4 V, which is a significant improvement compared to the MFIS structure with a random orientation. The difference in the electrical properties of the MFIS structures with both types of orientation is discussed in detail. The results obtained from this study indicate that the Au/BTO/STO/p-Si MFIS structure with high c-axis orientation has good potential for use in non-volatile memory applications.