Effect of temperature on the electrical properties of a metal-ferroelectric (SrBi₂Ta₂O₉)-insulator (HfTaO)-silicon capacitor

A metal-ferroelectric (SrBi₂Ta₂O₉)-insulator (HfTaO)-semiconductor capacitor was fabricated, and the temperature dependence of its electrical properties was investigated. Within the temperature range of 300–220 K, the maximum memory window is up to 1.26 V, and it could be attributed to a higher coercive field of the ferroelectric film at a lower temperature, which is induced by the deeper and more box-shaped potential well based on the defect-domain interaction model. The memory window decreases with increasing temperature from 300 to 400 K, and the larger sweep voltage leads to a smaller memory window at a higher temperature, which could be attributed to temperature-dependent polarization of the ferroelectric film and charge injection from an Si substrate of the capacitor. With the temperature increasing from 220 to 400 K, the leakage current density increases with temperature by about one order, and the corresponding conduction mechanism is discussed. The results could provide useful guidelines for design and application of ferroelectric memory. (paper)