Charge storage behaviors of Ge nanocrystals embedded in SiO2 for the application in non-volatile memory devices

Ge nanocrystals distributed in the SiO2 of metal-oxide-semiconductor structure are synthesized by low-energy Ge ion implantation with various energies and doses. Their charge storage behaviors are influenced by both the ion implantation dose and energy. The larger flatband voltage shift achieved by increasing either the implantation dose or energy is explained by the locations and concentration of the charge trapping sites. The smaller charge loss achieved by decreasing the implantation dose or increasing the implantation energy is explained by the co-existence of the charge leakage to the gate electrode and the lateral charge loss to the adjacent Ge nanocrystals.