Flicker Noise and Its Degradation Characteristics Under Electrical Stress in MOSFETs With Thin Strained-Si/SiGe Dual-Quantum Well

This letter reports on the low-frequency flicker-noise characteristics in fresh and electrically stressed pMOSFETs with thin strained-Si (~4 nm)/Si
_0.6
Ge
_0.4
(~4 nm) dual-quantum-well (DQW) channel architectures. Normalized power spectral density (NPSD) of I
_d
fluctuations (S
_ID
/I
_d

²
) in fresh DQW devices exhibits significant improvement (by >10
²
times) due to buried channel operation at low V
_g
. At high V
_g
, the NPSD enhancement reduces as carriers populate in the parasitic surface channel. Upon electrical stress, noise behavior in DQW devices was found to evolve from being carrier number-fluctuation dominated to mobility- fluctuation dominated. This was accompanied by the observation of a "less-distinct" buried-channel operation, indicating a potential stability issue of the Si/SiGe structure.