Structural and Charging Stability of Metal Nanodot Memory in SiO2; First-Principles Study

Metal nanodots are promising systems for future non-volatile memory devices. However, metal-atom dissociation from metal nanodots induces serious degradation during repetitious charge injection. We study which metal nanodot is thermally stable in SiO 2 and which kind of metal has large charge retention, using the first-principles calculations. We show that nanodots made of metal atoms with a large number of d-electrons, such as Au, are unstable. On the other hand, nanodots made of metal atoms with small number of d-electrons, such as W, have both large structural and large charge-retention stability. These features are closely related to the competition between the metal-metal, metal-Si, and metal-O interactions.