1/f Noise Sources

1/f noise is a fluctuation in the bulk conductance of semiconductors and metals. This noise could be a fluctuation in the number of the free electrons or in their mobility. Many experimental studies on homogenous layers have proved that the 1/f noise is a fluctuation in the mobility. There is no theoretical model of mobility 1/f noise. The McWhorter model for 1/f noise in MOSTs simply adds generation-recombination spectra from surface states. According to this model, estimates of the noise magnitude give unrealistic values. More important, the McWhorter model is a model on number fluctuations, because GR noise always is a fluctuation in number. There is no experimental proof of number fluctuations in the 1/f noise of MOSTs.