Electrical properties of SrBi₂Ta₂O₉ thin films deposited on Si(100) substrates by rf magnetron sputtering

Abstract

Recently, metal-ferroelectric-semiconductor (MFS) structures have attracted much attention because of its potentials as nonvolatile memory device with nondestructive readout operation. In the present study ferroelectric SrBi₂Ta₂O₉ (SBT) thin films are grown on p-type (100) Si substrates by rf magnetron sputtering method at different deposition conditions. The crystallinity of the films is studied using grazing incidence X-ray diffraction (GIXRD) pattern. The spectra show the films are polycrystalline with dominant orientation along (115) plane. The capacitance-voltage (C-V) characteristics of Al/SBT/Si capacitors were measured at 100 kHz. The (C-V) characteristic of Al/SBT/Si capacitor post-annealed at 700-800°C shows a hysteresis nature with a clockwise rotation and the memory window of the hysteresis loop is 0.88 V when the gate voltage is ± 5 V. The interface trap density (Dit) calculated by using Hills method at room temperature and a value in the order of [10¹¹-10¹² eV⁻¹cm⁻² was found at mid gap region depending on the crystallization temperature. The surface morphology was investigated by atomic force microscope (AFM). The study showed the potential of SBT for application in metal-ferroelectric-silicon nonvolatile memory devices.