Question

In semiconductors, light is emitted when:

• A. Holes move from valence to conduction band
• B. Electrons recombine with holes
• C. Photons collide with atoms
• D. Energy band gap increases

Hint:

Light emission in semiconductors occurs when electrons recombine with holes, releasing energy in the form of photons.

Answer 1

The Correct Option is B

In semiconductors, light emission occurs during the process of recombination of electrons with holes. When an electron from the conduction band falls back into a hole in the valence band, it releases energy in the form of a photon. This is the basic principle behind light emission in devices such as light-emitting diodes (LEDs).
- Holes move from valence to conduction band refers to the process of electron excitation, not light emission. This process requires energy input, rather than releasing energy in the form of light.
- Electrons recombine with holes is the correct process that leads to light emission in semiconductors.
- Photons collide with atoms is not a direct process leading to light emission in semiconductors, though photons may interact with atoms in other contexts.
- Energy band gap increases refers to a change in material properties, but it does not directly cause light emission. In fact, an increased band gap typically decreases the likelihood of light emission in semiconductors.
Thus, the correct answer is Electrons recombine with holes.