A pure semiconductor

Draw the Energy bands 'diagrams for a (i) pure semiconductor , (ii) insulator , How does the energy band, for a pure semiconductor , get affected when this semiconductor is doped with (a) an acceptor impurity (b) donor impurity ? Hence discuss why the 'holes' and the 'electrons' respectively, become the 'majority change carries' in these two cases ? Write the two processes involved in the formation of p-n junction.

At low temperature, pure semiconductors are ___

The resistance of pure semiconductor at absolute zero is

the process of addding impurities to the pure semiconductor is called

The process of adding impurities to the pure semiconductor is called

Why is it required to add impurity in pure semiconductor? Mention it's condition and explain what are impure semiconductors?