SILC decay in Ge-based MOS devices with La2O3 gate dielectrics subjected to constant voltage stress

The effect of constant voltage stress on Pt/La₂O₃/n-Ge MOS devices biased at accumulation is investigated and reported. It is found that the stress induced leakage current (SILC) initially increases due to electron charge trapping on pre-existing bulk oxide defects. After 10 s approximately, a clear decay of SILC commences which follows a t^-n power law, with n lying between 0.56 and 0.75. This decay of SILC is not changed or reversed when the stressing voltage stops for short time intervals. The effect is attributed to the creation of new positively charged defects in the oxide because of the applied stressing voltage, while other mechanisms proposed in the past are proved insufficient to explain the experimental data.