LED chips, or Light Emitting Diodes, work by a process called electroluminescence, which involves the emission of light when an electric current passes through a semiconductor material.
Here's a breakdown of the process:
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Semiconductor Materials: LED chips are made from semiconductor materials, typically composed of elements from groups III and V of the periodic table (e.g., gallium arsenide (GaAs), gallium phosphide (GaP), or gallium nitride (GaN)). These materials have special electrical properties that allow them to control the flow of current.
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The p-n Junction: The core of an LED chip is a p-n junction. This junction is formed by joining two differently doped semiconductor materials:
- p-type material: This material is doped with impurities that create an abundance of "holes" (positive charge carriers).
- n-type material: This material is doped with impurities that create an abundance of free electrons (negative charge carriers).
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Applying Voltage: When a forward voltage (positive voltage to the p-side, negative voltage to the n-side) is applied across the p-n junction, electrons from the n-side and holes from the p-side are pushed towards the junction.
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Recombination and Light Emission: At the junction, electrons and holes combine. When an electron recombines with a hole, it falls into a lower energy level, releasing energy in the form of a photon (a particle of light). This process is called electroluminescence.
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Wavelength and Color: The wavelength (and therefore the color) of the emitted light depends on the energy band gap of the semiconductor material used. Different materials emit different colors of light. For example:
- Gallium arsenide (GaAs) emits infrared light.
- Gallium phosphide (GaP) emits red or yellow light.
- Gallium nitride (GaN) emits blue or green light.
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Encapsulation: The LED chip is typically encapsulated in a plastic lens or epoxy to protect it from the environment and to focus the emitted light.
In short, an LED chip converts electrical energy into light by using the properties of semiconductor materials. When a current flows through the chip's p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific semiconductor material determines the color of light emitted.
