Discussion
n-channel MOSFET is preferred than p-channel MOSFET because :
Answer: D
The n-channel device is preferred because the electron mobility in Si is larger than the mobility of holes.
In silicon, electrons have a mobility of about 1350 cm\(^{2}\)/V·s and holes about 480 cm\(^{2}\)/V·s. Since drain current is proportional to carrier mobility, an n-channel MOSFET of the same size carries two to three times the current, switches faster and has a lower on-resistance than a p-channel device.
Input impedance is not the reason: in both types the gate is insulated by oxide, so both have extremely high input impedance. The option saying electron mobility is smaller than hole mobility states the fact the wrong way round.
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