Effect of annealing temperature on the structural and electrical properties of SrBi₂Ta₂O₉ thin films for memory-based applications

Abstract

Ferroelectric SrBi₂Ta₂O₉ (SBT) thin films were grown on p-type (1 0 0) Si substrates by radio frequency sputtering technique. The crystallinity of the films was studied using grazing incidence X-ray diffraction pattern. The spectra showed the films were polycrystalline with dominant orientation along (1 1 5) plane. The surface morphology was investigated by atomic force microscope. The chemical composition was studied by Rutherford back-scattering, which yielded a near stoichiometric composition of SBT. The capacitance-voltage characteristics of Al/SBT/Si capacitors measured at 100 kHz showed a hysteresis nature with a clockwise rotation and the memory window of the hysteresis loop was 0.88 V with the gate voltage ±5 V. The interface trap density was calculated by using Hills method at room temperature and a value in the order of 10¹¹-10¹² eV^-1 cm^-2 was found depending on the crystallization temperature at midgap region.