Question

A PN junction has a thickness of the order of:

Answer 1

Hint: A PN junction diode is a kind of semiconductor diode, which has two terminals. It allows the flow of current in one direction and blocks the flow of current in the other opposite direction, thus acting as a switch. The ability of a semiconductor to behave as a switch depends on the thickness of the junction as discussed below.

Complete step-by-step solution:
We know that there are two types of semiconductors depending on the nature of the charge carrier due to the doping of the semiconductor. Namely the n-type and the p-type. In the n-type the majority charge carriers are electrons and in the p- type, the majority charge carriers are the holes.
In the p-n junction semiconductor diode, the p-type and the n-type semiconductor are joined. This results in the formation of the p-n junction or the depletion junction between the diodes, due to the movement of the positive and negative charges to the opposite terminals. In other words the n-type and the p-type, are separated by a small region called the depletion region.
Thus the depletion region induced due the motion of electrons is very small often in the order of micrometers.

Note: The ability of the diode to act as a switch depends on the thickness of the depletion layer. When the diode is forward biased, the depletion layer is smaller, and hence the charges can flow through it easily. However, during the reverse bias, the depletion layer increases in the width making it harder for the charges to pass through.