Question

Carbon and silicon both are members of the IV group of the periodic table and have the same lattice structure. Carbon is an insulator whereas silicon is a semiconductor. Explain.

Answer 1

Comparison of Electrical Properties: Carbon vs Silicon

Carbon:
In diamond (a form of carbon), the atoms are bonded in a three
-dimensional tetrahedral lattice where each carbon atom forms four strong covalent bonds. This stable structure results in a large band gap between the valence band and the conduction band. Because the band gap is so wide, electrons cannot easily move to the conduction band, making diamond an insulator.

Silicon:
Silicon also forms a similar tetrahedral covalent lattice. However, it has a smaller band gap compared to diamond. At room temperature, some electrons in silicon can acquire enough thermal energy to jump from the valence band to the conduction band. This makes silicon a semiconductor, capable of conducting electricity under suitable conditions.

Conclusion:
The key difference in electrical properties arises from the band gap size:

• Carbon (diamond): Large band gap → Insulator
• Silicon: Smaller band gap → Semiconductor