1/f noise in Si/sub 0.8/Ge/sub 0.2/ pMOSFETs under Fowler-Nordheim stress

The 1/f noise in Si/sub 0.8/Ge/sub 0.2/ pMOSFETs was found to be lower than in allsilicon (Si) pMOSFETs, before and after Fowler-Nordheim (F-N) stress. The minimum noise in the Si/sub 0.8/Ge/sub 0.2/ pMOSFET occurred at the thinnest unconsumed Sicap of approximately 2 nm, because of the reduced-oxide trap density (N/sub ot/) near the Fermi level (E/sub F/) in the device. However, all samples in this study, including the Si control and the Si/sub 0.8/Ge/sub 0.2/ pMOSFETs with different unconsumed Si-cap thicknesses of 21-64 A, revealed almost identical relative changes in 1/f noise due to the stress, despite the relatively wide range of initial noise values. This suggests identical relative changes in N/sub ot/ at the E/sub F/ in the devices during F-N stress.