Particle Size and Morphology of Iridium Oxide Nanocrystals in Non-Volatile Memory Device

Abstract

The aim of this work is to investigate the particle size and morphology of the nanocrystals in the non-volatile memory device by annular dark field (ADF) scanning transmission electron microscopy (STEM) and conventional transmission electron microscopy (CTEM) techniques. With respect to TEM investigation, statistical analysis on STEM image can acquire the size and density of nanocrystals more accurately than on TEM image. In addition, ADF STEM images successfully provide powerful evidences revealing the structure of IrO x nanocrystals as a core shell structure, where the inner structure is rich in Ir and the outer area is abundant in O or Al. This method could be one of the efficient way for examining the nanocrystals with a complicated cored structure.

Theoretical Study of Structure, Stability, and the Hydrolysis Reactions of Small Iridium Oxide Nanoclusters

“…When more oxygen atoms are added, they locate around the central iridium clusters in either bridging or terminal types. Our calculations are in good agreement with the recent experimental observation of iridium oxide nanocrystals as a core shell structure …”

“…Our calculations are in good agreement with the recent experimental observation of iridium oxide nanocrystals as a core shell structure. 21 3.2. Stability.…”

“…20 Recently, Banerjee and co-workers have reported that annular dark field scanning transmission electron microscopy images provide evidence revealing the structure of IrO x nanocrystals as a core shell structure, where the inner structure is rich in Ir and the outer area is rich in O. 21 Despite some efforts, the structures and properties of iridium oxide nanoparticles are still far from complete understanding.…”

Effects of Iridium Oxide Thickness and Post Annealing Temperature on the Size and Density of Core-Shell IrOx-Based Nanocrystals of a Nonvolatile Memory Device

“…Difference of these four TEM images is the dimension of the size of nanocrystals, consistent with the previously published observation (5). Statistical analysis on STEM image can acquire the size and density of nanocrystals more accurately than on TEM image because the growing nanocrystals are in different orientation and it therefore cannot be measured accurately due to the invisible condition (2). Thereby, average grain sizes of nanocrystals were found to be 2.2nm, 2.6nm, 3.2nm, and 3.6nm, respectively, but the density of IrO x nanocrystals decreased with increasing PDA temperature.…”

“…Iridium and iridium oxide (Ir and IrO x ) nanocrystals were firstly reported by Korotcov et al (1) and they have been widely studied for the memory applications. Particle size and density of iridium oxide nanocrystals in non-volatile memory device have been well studied (2). Meanwhile, the morphology of iridium oxide nanocrystals is revealed as core-shell structure through high angle annular dark field (HAADF) STEM images, and the composition of inner area is rich in Ir element and the outer area is abundant in O or Al element.…”