Question

The barrier potential of a p-n junction depends on:
(a) type of semiconductor material
(b) amount of doping
(c) temperature
Which one of the following is correct?
A. (a) and (b) only
B. (b) only
C. (b) and (c) only
D. (a), (b) and (c) only

Answer 1

In a semiconductor there exists a region at the middle of the junction which is devoid of mobile charge carriers and contains minority charge carriers. This is called the depletion region. The depletion region is big in case of n type of semiconductors while in case of p type of semiconductors its width is thin. The role played by the depletion region determines the electrical conductivity of the pn junction diode.

Complete answer:
The electric field that is produced in the depletion region acts as a barrier. External energy must be exerted to allow the electrons to get through the barrier of the electric field. The potential difference required for the electrons to be passed across the electric field is called the potential barrier.This potential barrier for the semiconductor depends upon the type of semiconductor that is the material used, how doping is done and what is the temperature of the semiconductor.

So, taking all this into account, the correct option is D that it depends on all the parameters given.

Note: Broadly two types of elements are used for making the desired pn junction. These are group 13 and group 15 elements by doping into the group 14 elements. The group 14 element such as silicon has 4 valence electrons in the outermost shell and when group 13 is introduced then there is one electron less to fill the octet and thus holes act as majority charge carriers.