Physical Origin of the Excess Thermal Noise in
Short Channel MOSFETs
IEEE Electron Device Letters, Vol. 22, No. 2, pp. 101-103, Feb. 2001.
While the drain thermal noise of long channel MOSFETs
agrees with the van der Ziel model,
considerably larger noise has been observed in MOSFETs
with channel lengths below 1.7um.
Recent compact modeling approaches have explained
this phenomenon using local voltage noise sources.
However, the use of local
voltage noise sources in device modeling suffers from the
spatial correlation of the noise sources.
This results in a dominant noise contribution
near the drain junction, which is more significant when the hot
carrier effects are included.
By contrast,
quasi-2D numerical simulation results for HEMT devices have
suggested that the drain noise of the FET is not
in fact dominated by the drain-side but rather by the source-side contributions.
Recent numerical noise simulation results have qualitatively demonstrated
the observed excess thermal noise in 0.25um MOSFETs based on
the Hydrodynamic (HD) formulation.
However, the physical mechanism responsible for
such excess noise has not been identified.
This paper investigates the physical origin of the excess noise by
comparing the differences between local and non-local carrier transport
models in noise simulation.
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