Question Detail
Question
Which of the following is true about intrinsic semiconductor?
i. Each semiconductor atom undergoes paired sharing of electrons with four neighbouring atoms.
ii. Conduction is due equally to holes and electrons.
iii. Group V atoms in the semiconductor share four electrons with four neighbouring atoms with an extra electron.
iv. Band structure is between that of metals and insulators.
i. Each semiconductor atom undergoes paired sharing of electrons with four neighbouring atoms.
ii. Conduction is due equally to holes and electrons.
iii. Group V atoms in the semiconductor share four electrons with four neighbouring atoms with an extra electron.
iv. Band structure is between that of metals and insulators.
Correct Answer
Option B is the correct answer.
Detailed Explanation
For an intrinsic semiconductor like pure silicon or germanium:i. Each atom forms four covalent bonds by sharing electrons with four neighboring atoms. This is true.ii. At non-zero temperatures, thermal energy breaks some covalent bonds, creating electron-hole pairs. Conduction occurs due to both free electrons and holes, and their numbers are equal. This is true.iii. This statement describes n-type doping, where a pentavalent (Group V) impurity atom has an extra electron for conduction, and is not characteristic of an intrinsic semiconductor. This is false.iv. Semiconductors have a band gap that is smaller than insulators but larger than metals (which have overlapping bands or no band gap). This is true.Therefore, statements i, ii, and iv are true.
Hint
Recall the atomic structure, charge carriers, and energy band theory for intrinsic semiconductors.