Question

The barrier potential of a p-n junction depends on:
$(a)$type of semiconductor material
$(b)$amount of doping
$(c)$temperature

$A.(a)$ and $(b)$ only
$B.(b)$ only
$C.(a)$ and $(c)$ only
$D.(a),(b)$ and $(c)$

Answer 1

To solve this problem we must have the idea of p-n junction and barrier potential. A boundary between p-type and n-type of semiconductor materials inside a single semiconductor is called p-n junction. The potential difference which is created across the p-n junction due to the diffusion of electrons and holes is called potential barrier.

Complete step-by-step answer:
We have to determine the factors on which the barrier potential of a p-n junction depends. To find out the required answer, we have to analyse the given factors in the options one by one.
Analysing option $(a)$ type of semiconductor material:-
From the experiments it is clear that different semiconductor materials have different values of barrier potential. For example, the potential barrier for Germanium is $0.3V$ and that for Silicon is $0.7V$. Therefore, it is clear that barrier potential does depend on the type of semiconductor material.
Analysing option $(b)$ amount of doping:-
We know that width of depletion layer is inversely proportional to the doping in the material and potential barrier is dependent on depletion layer. Hence, the potential barrier does depend on the amount of doping.
Now, analysing the last option $(c)$ temperature:-
We also know that depletion is directly proportional to the temperature. i.e., depletion rises with rise in temperature. Therefore, the potential barrier is also dependent on temperature.
Hence, from the above discussion we got to know that potential barrier does depend on all the three given factors, type of semiconductor substance, amount of doping and temperature.
Hence, option $(D)$ is correct.

So, the correct answer is “Option D”.

Note: We should not be confused about the fact that potential barrier and depletion layer are related to each other in accordance with the properties on which they depend. The charge transfer of electrons and holes across the p-n junction is called diffusion. At potential barriers there is no free charge carriers can rest. We should also be clear about the difference between semiconductor and metals and their properties.