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

摘要

This letter reports on the low-frequency flicker-noise characteristics in fresh and electrically stressed pMOSFETs with thin strained-Si ($sim$4 nm)/ $hbox{Si}_{0.6}hbox{Ge}_{0.4}$ ( $sim$4 nm) dual-quantum-well (DQW) channel architectures. Normalized power spectral density (NPSD) of $I_{d}$ fluctuations ( $S_{rm ID}/I_{d}^{2}$) in fresh DQW devices exhibits significant improvement (by $> hbox{10}^{2}times$) 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.