Effect of the Physical and the Chemical Structures of Ni Nanocrystals on the Nonvolatile Memory Characteristics for Small-molecule Nonvolatile Memorycells Embedded with Ni Nanocrystals

Abstract

We determined the effects of the evaporation rate of the Ni layer and the presence of in-situ O<SUB>2</SUB> plasma oxidation on the physical and the chemical structures of Ni nanocrystals embedded in smallmolecule (Alq_3: aluminum tris(8-hydroxyquinoline)) memorycells. The Ni nanocrystals produced by an evaporation rate of 0.1 Å/s for the Ni layer with in-situ O_2 plasma oxidation were well isolated from one another by a NiO tunneling barrier. The small-molecule memorycell embedded with isolated Ni nanocrystals surrounded by a NiO tunneling barrier demonstrated a memory margin (I_(on)/I_(off) ratio) of ?1 × 10^3, a retention time of more than 10^5 sec, and an endurance of more than 2 × 10^2 erase-and-program cycles.