Question

The forbidden energy band gap in conductors

Answer 1

Hint: Forbidden energy gap determines whether the material is conductor or semiconductor or insulator. When a small amount of energy is supplied, the electrons can easily jump the forbidden gap. It is the energy range in which no electrons are present.

Complete step-by-step answer:
Forbidden energy gaps are also known as energy gaps or bandgaps. This is an energy range in a solid where no electrons are present. This band gap generally refers to the energy difference between the top of the valence band and bottom of the conduction band. It is the minimum energy required to excite an electron from a valence band to the conduction band. This electron serves as a charge carrier to conduct electric current.

Additional information:
According to the band gap semiconductors can be classified as direct band gap materials and indirect band gap materials.
For direct band gap semiconductors, the conduction band minima and valence band maxima occur at the same value of momentum. So, the electron can return from the conduction band to the valence band without changing its momentum and it will release energy in the form of light. Examples are GaAs, GaAsP.
For Indirect band gap semiconductors, conduction band maxima and valence band minima occur at different values of momentum. So, the electron can return to the valence band after changing its momentum. This will release a heat particle such as phonon. Examples are Si, Ge.

Note: In conductors there is no forbidden gap. In conductors the valence band and conduction band overlaps. For insulators, the band gap will be larger. So, the electrons can’t move to the conduction band. The materials with small energy band gaps are known as semiconductors.