JEE Advanced levelSingle correct optionDifficulty 3 of 3ss217
Three solids X, Y and Z have the following band structures: X has a filled valence band, an empty conduction band and a gap of 0.7eV; Y has a gap of 5.5eV; Z has a partly filled band overlapping an empty band. X, Y and Z are respectively
Asemiconductor, insulator, conductor
Binsulator, semiconductor, conductor
Cconductor, semiconductor, insulator
Dsemiconductor, conductor, insulator
Answer: A
A small gap (about 0.7 eV) can be crossed by thermal excitation: semiconductor. A very large gap (5.5 eV) prevents excitation: insulator. A partly filled or overlapping band allows free electron movement: conductor.