Critical discussion on unified 1/f noise models for MOSFETs

Recently, unified noise models, like BSIM3, have been proposed in literatur e to describe the 1/f noise of n- and p-type MOSFETs in all operating regim es. These models combine carrier number fluctuations and correlated mobilit y fluctuations. The latter are induced by Coulomb scattering of free carrie rs at trapped interface charge. The unified 1/f noise models assume implici tly that the mobility, limited by Coulomb scattering, does not depend on th e inversion carrier density. However, this assumption is not correct in vie w of theoretical calculations and recent experimental results. In this pape r, we show that the correlated mobility fluctuations are negligible, if the correct dependence on inversion carrier density is taken into account for the Coulomb scattering limited mobility. Consequently, the unified 1/f nois e models cannot predict the 1/f noise observed experimentally in p-type MOS FETs, except if nonphysical fitting parameters are used. This paper serves as a critical discussion on the unified 1/f noise models for MOSFETs, Here it is not our intention to propose a new 1/f noise model.