lsqm
Newbie level 4
Razavi book says: When inversion layer is being formed in a MOSFET, as the Vg becomes more positive, the holes will be repelled from the gate area leaving the negative ions behind and it forms a depletion region. When the negative ions are present in that region, why is it called depletion region ? If the negative ions are immobile because the Vg has not yet reached the threshold voltage, does that voltage have enough energy to repel the positive ion from gate area ?(don't we have to mobilize the p ions to repel from gate area ? )