Correct option is C
In semiconductor physics, particularly when discussing materials like silicon, the energy gap, also known as the band gap, is the energy difference between the valence band (the highest energy band fully occupied by electrons at absolute zero temperature) and the conduction band (the lowest energy band that can be occupied by electrons that have gained sufficient energy to contribute to conduction).
The band gap is a key feature because it determines the electrical conductivity of the material. In a semiconductor like silicon:
The valence band is full of electrons at zero Kelvin.
The conduction band is empty at zero Kelvin.
Electrons in the Energy Gap:
In the energy gap, there are no allowed energy states for electrons. This means that there are no electrons residing in the energy gap at any given time under normal conditions.
Electrons must either be in the valence band or have enough energy to jump to the conduction band.
Given the definition and properties of the band gap in semiconductors:
(c) Zero is the correct answer.
Electrons cannot exist in the energy gap under standard conditions as there are no available energy states within this gap.
This characteristic is what defines the electrical properties of semiconductors, allowing them to act neither completely like insulators nor like conductors, but with a controlled conductivity based on the energy supplied (like light or heat) that can excite electrons from the valence band into the conduction band.
