Articles you may be interested inStructural and electrical characteristics of high-k Tb 2 O 3 and Tb 2 TiO 5 charge trapping layers for nonvolatile memory applications
In this paper, we proposed a metal-oxide-high-k-oxide-silicon (MOHOS)-type memory structure fabricating a high-k Tb2O3 charge trapping layer for flash memory applications. The high-k Tb2O3 MOHOS-type memories annealed at 800 °C exhibited large threshold voltage shifting (memory window of ∼1.41 V operated at Vg=8 V at 0.1 s), excellent data retention (charge loss of ∼10% measured time up to 104 s and at 85 °C), and good endurance characteristics (program/erase cycles up to 105) because of the high probability and deep trap level for trapping the charge carrier due to the formation of the crystallized Tb2O3 with a high dielectric constant of 11.8.
In this study, we investigated the structural properties and electrical characteristics of metal/oxide/high-k material/oxide/silicon (MOHOS)-type memory devices incorporating Tb2O3 and Tb2TiO5 films as charge storage layers for nonvolatile memory applications. X-ray diffraction and x-ray photoelectron spectroscopy revealed the structural and chemical features of these films after they had been subjected to annealing at various temperatures. From capacitance-voltage measurements, we found that the MOHOS-type memory devices incorporating the Tb2TiO5 film and that had been annealed at 800 °C exhibited a larger flatband voltage shift of 2.94 V (Vg=9 V for 0.1 s) and lower charge loss of 8.5% (at room temperature), relative to those of the systems that had been subjected to other annealing conditions. This result suggests that Tb2TiO5 films featuring a thinner silicate layer and a higher dielectric constant provide a higher probability for trapping of the charge carrier and deeper electron trapping levels.
In this letter, we proposed a metal-oxide-high-k-oxide-silicon-type (MOHOS) memory structure incorporating a high-k Yb2TiO5 charge trapping layer and the subsequent postdeposition annealing treatment. The effect of postdeposition annealing on the structural properties of Yb2TiO5 charge trapping layers was explored by x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy. The Yb2TiO5 MOHOS-type device annealed at 800 °C exhibited a larger memory window of 2.8 V and a smaller charge loss of 10% than did those prepared at other annealing temperatures. This outcome is attributed to the higher probability for trapping the charge carrier due to the formation of a well-crystallized Yb2TiO5 structure and a thin low-k interfacial layer.
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