second order effects

[raghunaandan]

why the channel length shortens as we increase Vds ? what is impact of ionization ?

 

[csolis_GT]

why the channel length shortens as we increase Vds ?

When you increase vds, the drain to substrate voltage increases which increases the depletion region between the drain and substrate. This forces the pinch-off point to move into the source direction, reducing the channel length.

 

[erikl]

Re: impact ionization

what is impact of ionization ?

Impact ionization is one of the effects responsible for the short-channel_effect, see here.