Question 21 of 209
For extrinsic semiconductors; when doping level is increased;
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Answer: (D) Fermi-level of - type semiconductors will go downward and Fermi-level of - type semiconductor will go upward.
In n-type semiconductor pentavalent impurity is added. Each pentavalent impurity donates a free electron. So the Fermi-level of -type semiconductor will go upward.
& In p-type semiconductor trivalent impurity is added. Each trivalent impurity creates a hole in the valence band. So the Fermi-level of p-type semiconductor will go downward.
& In p-type semiconductor trivalent impurity is added. Each trivalent impurity creates a hole in the valence band. So the Fermi-level of p-type semiconductor will go downward.