question_answer

Which one of the following is true about the p-type and n-type semiconductor?

A) n-type semi-conductor have holes in majority

B) The concentration of electrons and holes are equal in both n-type semiconductors

C) n-type semiconductors have free electrons in majority

D)  n-type semiconductor has excess negative charge

Correct Answer: C

Solution :

                When an impurity atom with 5 valence electrons (as arsenic) is introduced in a germanium crystal, four of the five valence electrons of the impurity atom form covalent bonds with one each of valence electron of germanium while the fifth electrons is free giving rise to n-type semiconductor. Hence, n-type semiconductor has free electrons in majority. Note: p-type semiconductors have holes in majority.