Under strong electric fields, carrier drift velocity stops increasing in proportion to the field and levels off at about 1×10⁷ cm/s. In short-channel MOSFETs it makes drain current smaller than the square law predicts.
Field: MOSFET
The proportionality holds only at low fields; for electrons in silicon the increase slows above roughly 10⁴ V/cm and the velocity saturates at about 1×10⁷ cm/s (velocity saturation).
What is the drift velocity of electrons with a mobility of …At low fields drift velocity is proportional to field, but at high fields carriers lose energy by emitting optical phonons, and electron velocity in silicon levels off at about 1×10⁷ cm/s (velocity saturation).
What happens to the drift velocity of electrons in silicon …In short-channel devices velocity saturation pushes the dependence toward linear, and mobility degradation and parasitic resistance add further deviations, so real designs use detailed models such as BSIM.
When a long-channel MOSFET operates in the saturation regio…Mobility Saturation region GaAs (gallium arsenide) Threshold voltage Body effect Channel-length modulation CMOS DIBL Flat-band voltage GIDL (gate-induced drain leakage)