Hi,

The answer is contained in your question. For submicron transistors, saturation typically occurs due to onset of velocity
saturation rather than due to pinchoff of the channel. Naturally, as the mobility of electrons and holes is very different,
so is the onset of saturation and the related behavior.

Hope this answers your question.

Vivek

Hi,

What Vivek stated is totally correct. Let me try to complete the whole picture by taking into account the following:
since the saturation velocity is the one driving the channel length modulation for sub-micron transistors and that the electrons mobility is larger than the pmos one, then the saturation velocity for the pmos will be smaller than the one for the nmos.

Therefore, under same bias conditions and geometry, it will be the pmos the one to get its channel modulated first. Hence, more susceptible to lenght modulation or equivalently larger modulation parameter.

Tosei