Led Emission
LED emits light when electrons recombine with holes releasing energy equal to:
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About This Question
- Subject
- physics
- Chapter
- semiconductor electronics
- Topic
- led emission
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
Band gap energy
Light Emitting Diodes (LEDs) are specially designed p-n junctions made from compound semiconductors (like GaAs or GaP).
- When forward biased, electrons are injected into the p-region and holes into the n-region.
- Charge carriers recombine near the junction.
- In direct band gap materials, this recombination releases energy in the form of photons rather than heat.
- The energy of the emitted photon is approximately equal to the band gap energy Eg of the material: hν≈Eg.
- The color of light depends on the band gap.
This hard difficulty physics question is from the chapter semiconductor electronics, covering the topic of led emission. It appeared in the 2025 exam.
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