Carbon, silicon and germanium have four valence electrons each. Their valence and conduction bands are separated by energy gap Eg. If we represent $Eg_{(c)}, Eg_{(si)}$ and $Eg_{(ge)}$ as their repective energy gaps, then which of the following is true
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $(Eg)_c > (Eg)_{si} > (Eg)_{ge}$
Given:
Elements: Carbon (C), Silicon (Si), Germanium (Ge)
All have 4 valence electrons, but energy gaps differ:
Energy gap: $E_g$(C) > $E_g$(Si) > $E_g$(Ge)
Reasoning:
- Carbon (diamond) has a very large energy gap (~5.5 eV) → insulator
- Silicon has moderate energy gap (~1.1 eV) → semiconductor
- Germanium has smaller energy gap (~0.66 eV) → semiconductor
Correct relation: $E_g(\text{C}) > E_g(\text{Si}) > E_g(\text{Ge})$