A simple PN junction diode is fabricated using ………. semiconductor and can be used as a …….a.Intrinsic, unidirectional switchb.Intrinsic, bidirectional switchc.Extrinsic, bidirectional switchd.Extrinsic, unidirectional switch

The correct answer is d. Extrinsic, unidirectional switch.

Here's why:

A PN junction diode is made from an extrinsic semiconductor, not an intrinsic one. An intrinsic semiconductor is pure and doesn't have any impurities, while an extrinsic semiconductor is doped with impurities to increase its conductivity.

A PN junction diode allows current to flow only in one direction, making it a unidirectional switch. It doesn't allow current to flow in the opposite direction, so it can't be a bidirectional switch.