A study of the memory effects of metallic core–metal oxide shell nanocrystals by a micelle dipping technique

Abstract

With a simple and conformal metal nanocrystal dipping of synthesized micelles, nonvolatile memory characteristics originating from a metallic cobalt (Co) core nanocrystal (NC) surrounded by a Co-oxide shell are investigated in this study. From transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS), it was confirmed that Co-oxide was made by oxygen plasma for polymer oxidation and that metallic Co wrapped with a Co-oxide shell was made by hydrogen annealing in order to reduce the Co-oxide. Energy band diagrams considering the extent of the coexistent metallic Co/Co-oxide were also analyzed in terms of how they correspond to each program/erase/retention case. These cases were verified by electrically measured data. These results can provide a guideline for the design and optimization of metal NC embedded memory.

Improved performance of non-volatile memory with Au-Al2O3 core-shell nanocrystals embedded in HfO2 matrix

“…Particularly, metallic NCs have several advantages over other counterparts, such as higher density of states, large work function and strong charge confinement, which allows memory devices to operate with higher charge density, lower power and better retention. 5 As an alternative way of improving memory performance, NC core-shell structure has been developed and adopted, 4,21,22 which effectively improves the retention of NC memory due to the additional barrier. However, most of the shell formations are based on the native oxidation by laser irradiation or annealing, which limits the shell materials and the performance improvement of memory devices.…”