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प्रश्न
Answer in brief.
On which factors does the wavelength of light emitted by a LED depend?
उत्तर
The intensity of the emitted light is proportional to the recombination rate and thus to the forward current of the diode. The colour of the light emitted by an LED is determined by the compound semiconductor material used as well as its composition (and doping levels), as shown below:
Typical semiconductor materials and emitted colours of LEDs
| Material | Emitted colour(s) |
| Gallium arsenide (GaAs), Indium gallium arsenide phosphide (InGaAsP) | Infrared |
| Aluminum gallium arsenide (AlGaAs) | Deep red, also IR laser |
| Indium gallium phosphide (InGaP) | Red |
| Gallium arsenide phosphide (GaAsP), aluminum indium gallium phosphide (AllnGaP) | Orange, red or yellow |
| Gallium phosphide (GaP) | Green or yellow |
| Aluminium gallium phosphide (AIGaP), zinc selenide (ZnSe), zinc selenide telluride (ZnSeTe), nitrogen impregnated gallium phosphide (GaP:N) | Green |
| Indium gallium nitride (InGaN), gallium nitride (GaN), sine sulphide (ZnS) | Blue and violet Longer wave lengths (green and yellow) are obtained by increasing the indium (In) content. Phosphor encapsulation produces white light. |
| Aluminium gallium nitride (AlGaN) | Ultraviolet |
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