Low-frequency noise mechanisms in Si and pseudomorphic SiGe p-channel field-effect transistors

Measurements of low frequency noise in Si and Si0.64Ge0.36 p-channel metal oxide semiconductor field effect transistors are compared with a model of carrier number fluctuations due to tunneling into an energy independent density of oxide trap states (Nox) and associated mobility fluctuations. The failure of the model to explain the data leads us to suggest that reduced noise in the SiGe device as compared to Si is primarily associated with an energy dependence of Nox and a displacement of the Fermi level at the SiO2 interface in the heterostructure relative to the Si control.