Substrate Current Model
Impact ionization is the physical mechanism for the generation of substrate current.
As the channel length of MOSFETs is reduced to the submicrometer regime, the electric field near the drain region causes impact ionization at a significant rate.
The substrate current can cause problem such as latch up, shift of threshold voltage, and the degradation of transconductance in short channel devices; The substrate current also contributes to the output conductance in the saturation region and the breakdown characteristics.
栅诱导漏极泄漏电流GIDL：