Memory characteristics of MOS capacitors with Ge nanocrystal-embedded Al2O3 gate layers

Ge nanocrystals (NCs) embedded in Al2O3 gate oxide layers used as the floating gate layers were prepared by the thermal annealing of Ge ions implanted in the gate oxide layers. Capacitance versus voltage ( C – V ) curves of the Ge NC-embedded metal–oxide–semiconductor (MOS) capacitors were characterized in this work. The C – V curves of the NC-embedded MOS capacitor show counterclockwise hysteresis loops at various sweep voltages, which indicates the presence of charge storage in the Ge NCs caused by the Fowler–Nordheim tunneling of electrons between the p-type Si substrate and the Ge NCs. In addition, capacitance versus time measurements were made for the Ge NC-embedded MOS capacitor to investigate its retention characteristics.