Charge storage characteristics of metal-oxide-semiconductor (MOS) structure containing Au nanocrystals on tunnel oxide composed of triply stacked SiO2, HfO2, and Al2O3 layers were studied. Significantly high charge injection and detrapping efficiency for program and erase operations along with a satisfactory long-term charge retention were obtained from the above MOS structure. It is attributed to the bandgap engineering of tunnel oxide with a multistacked concave barrier, from which the effective thickness of the tunneling barrier can be greatly reduced under a moderate bias, while a thick and high barrier is retained for charge retention.

Charge storage characteristics of metal-oxide-semiconductor (MOS) structures containing Au nanocrystals on tunnel oxide composed of Al2O3/HfO2/Al2O3 stacks in different thickness piling up sequences were investigated. A significant enhancement of charge injection efficiency for both electrons and holes without sacrificing charge retention performance was found in the sample with a relatively thicker (∼3 nm) Al2O3 sublayer adjacent to Au nanocrystals and a thinner (∼1 nm) Al2O3 sublayer in front of the Si substrate. It is attributed to the local enhancement of electric field induced by the embedded Au nanocrystals, which greatly modifies the effective barrier of tunnel oxide.

The micro grid system requires battery for energy storage and power management. In which, the bi-directional DC to DC converter is the key component for maintaining the DC bus voltage and controlling the charge and discharge of the battery with or without grid support. Parallel control of multiple DC to DC converters is a critical technique to enlarge the power capacity. This paper presents two capacity limitation control methods that multiple DC to DC converters can be paralleled with distributed battery banks. The first method is the capacity limitation control with cascaded load current sense needing no control interconnection. The second method is the capacity limitation control with master-slave and cascaded current command limitation. Two methods are presented to solve the limitation of droop control method and active current sharing method respectively, and can be extended without converter number limitation theoretically. Three prototype 240W bidirectional half-bridge DC to DC converters are built and paralleled in this paper. The proposed method is confirmed with some measured results.