Impact of the interfaces in the charge trap layer on the storage characteristics of ZrO2/Al2O3 nanolaminate-based charge trap flash memory cells

The charge trap flash memory cells incorporating high-k ZrO2/Al2O3 nanolaminate as charge trapping layers and amorphous Al2O3 as tunneling and blocking layers were prepared, investigated and optimized. The interfaces between ZrO2/Al2O3 nanolaminate play an important role in the charge storage characteristics. With increasing number of the interfaces in the charge trapping layer, the memory window increases first and then decreases due to electrostatic repulsion between the trapped electrons. A satisfactory retention performance was observed in the optimized cell structure, which was attributed to the deep quantum wells between the ZrO2/Al2O3 nanolaminate.

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► Nanolaminate-based charge trap flash memory cells incorporating a high-k ZrO2/Al2O3 nanolaminate as charge trapping layer and amorphous Al2O3 as tunneling and blocking layer.
► It is proposed that the charges are trapped by the ZrO2/Al2O3 interfaces.
► Excellent retention performance was attributed to appropriate distance of neighboring interfaces and deep quantum well as identified by measured valence band offsets and electron energy loss spectrum.