  1/f noise is a critical figure of merit for the performance of transistors
and circuits. For two-dimensional devices (2D-FETs), and especially for
applications in the GHz range where short-channel FETs are required, velocity
saturation (VS) effect can result in the reduction of 1/f noise at high
longitudinal electric fields. A new physics-based compact model is for the
first time introduced for single- to few- layer 2D-FETs in this study,
precisely validating 1/f noise experiments for various types of devices. The
proposed model mainly accounts for the measured 1/f noise bias dependence as
the latter is defined by different physical mechanisms. Thus, analytical
expressions are derived, valid in all regions of operation in contrast to
conventional approaches available in literature so far, accounting for carrier
number fluctuation (DN), mobility fluctuation (Dmu}) and contact resistance
(DR) effects based on the underlying physics that rules these devices. DN
mechanism due to trapping/detrapping together with an intense Coulomb
scattering effect, dominates 1/f noise from medium to strong accumulation
region while Dmu, is also demonstrated to modestly contribute in subthreshold
region. DR can also be significant in very high carrier density. The VS induced
reduction of 1/f noise measurements at high electric fields, is also remarkably
captured by the model. The physical validity of the model can also assist in
extracting credible conclusions when conducting comparisons between
experimental data from devices with different materials or dielectrics.
