Question

Recombination of electron-hole produces ____ in LEDs.

• A. Photons
• B. Protons
• C. Nucleus
• D. Junction capacitance

Hint:

LED Operation. Forward bias \(\rightarrow\) Injection of electrons and holes \(\rightarrow\) Recombination in junction region \(\rightarrow\) Energy released as Photons (light). Light color depends on semiconductor bandgap energy.

Answer 1

The Correct Option is A

A Light Emitting Diode (LED) is a semiconductor device that emits light when forward biased
Under forward bias, electrons from the n-region and holes from the p-region are injected across the p-n junction
In the junction region (or active layer), these electrons and holes recombine
When an electron recombines with a hole, it transitions from a higher energy level (conduction band) to a lower energy level (valence band)
In direct bandgap semiconductors used for LEDs, this energy difference is released primarily in the form of a photon (a quantum of light)
The energy (and thus color) of the photon corresponds to the bandgap energy of the semiconductor material
Protons and nuclei are related to atomic structure, not light emission in LEDs
Junction capacitance is an electrical property of the diode