Physical and electrical properties of Dy₂O₃ and Dy₂TiO₅ metal oxide-high-κ oxide-silicon-type nonvolatile memory devices

In this paper, we compare the physical and electrical properties of metal oxide-high-κ oxide-silicon (MOHOS)-type devices using Dy₂O ₃ and Dy₂TiO₅ films as charge-trapping layers. X-ray diffraction and x-ray photoelectron spectroscopy revealed the structural and compositional features of these films after annealing at various temperatures. MOHOS memory devices incorporating the Dy₂TiO ₅ trapping layer that had been annealed at 800 C exhibited a larger memory window of ~2.91 V (measured at a sweep voltage range of ±9 V), higher flatband voltage shift of 2 V (programming voltage at 9 V for 0.1 s), and smaller charge loss of ~10% (measured at room temperature after 10⁴ s), relative to those of the systems that had been subjected to other annealing conditions. This result suggests that the Dy₂TiO₅ film featuring a higher dielectric constant as well as a thinner silicate layer provides a higher probability of charge carrier trapping and deeper electron trapping levels. In addition, the centroid of trapped charge in the Dy ₂TiO₅ layer was extracted by the constant current stress method and compared with that of the Dy₂O₃ layer.