Physics (Essay) Paper 2 WASSCE (SC), 2018

Question 4

 

 

(a)  What is an intrinsic semiconductor?

 (b)  Distinguish between the p-type and n-type semiconductors.

 

Observation

 

A good percentage of the candidates provided the correct response. However, some candidates misfired as they gave textbooks description and theories of semiconductors without hitting the bull’s eye.
 
The expected answer

  (a)     Intrinsic semiconductor contains equal number of free electrons and holes
(b)    


p-type

n-type

Has holes as the majority carriers of electricity

Has electrons as the majority carriers of electricity

Impurity is trivalent

Impurity is pentavalent

Created by an acceptor impurity

Created by donor impurity

Carries a net positive charge

Carries a net negative charge