Electronics and Communication Engineering - Electronic Devices and Circuits - Discussion

Through the addition of donor impurity (i.e. Pentavalent atoms, valence electrons = 5) to semiconductors (valence electron = 4) the number of valence electrons will increase, 5+4 = 9, but the valence shell could only hold 8 Valence electrons, therefore another valence band/shell would be added for the additional 1 valence electron.

Thus it would create an additional energy level below the conduction band which is where the valence band is located.

Donor impurity means the impurity with five electrons i.e. phosphorus.

While p-type means the addition of impurity with three electrons I. E Boron (boron is known as acceptor impurity). So, both are correct but independent.

Why does, 'The addition of donor impurity creates additional energy levels below the conduction band. ' I mean how? Explain in detail

A refers to 'p' type semiconductor while R refers to 'n' type semiconductor. Both A and R are correct but independent.

Please provide the explanation for the answer.