Question

What are the valence-band and conduction-band occupancies in an insulator?

Options

• Electrons in the conduction band and holes in the valence band

• Conduction band partially filled

• Valence band and conduction band overlap

• Valence band completely filled; conduction band completely empty

Answer 1

An insulator has a completely filled valence band and a completely empty conduction band. Its large energy gap prevents electrons from moving into the conduction band under normal conditions.