Non-volatile memory structures with Ge NCs-HfO2 intermediate layer

The structure and charge storage properties of a trilayer structure with Ge nanocrystals embedded in HfO
₂
oxide were studied. The trilayer structure HfO
₂
/Ge-HfO
₂
/HfO
₂
/p-Si was prepared by magnetron sputtering and subsequent rapid thermal annealing at 600 °C. The TEM investigations reveal the formation of Ge NCs embedded in crystalline HfO
₂
at the position of the Ge-HfO
₂
layer. The capacitors were made by Al evaporation on both front and backside of the trilayer structure. The C-V characteristics show a counterclockwise hysteresis with large memory window of 0.85 V which is given only by the contribution of the Ge NCs embedded in HfO
₂
. The I-V characteristics show an asymmetric behavior, the currents are three times higher for the negative voltage than the positive one.