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CBSE Class 12-science Answered

Name the p-n junction diode which emits spontaneous radiations when forward biased. How do we choose the semiconductor, to be used in these diodes, if the emitted radiation is to be in the visible region?
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
answered-by-expert Expert Answer

The p-n junction diode, which emits spontaneous radiation when forward biased, is known as the light emitting diode or LED.

The visible light is from 0.45 µm to 0.7 µm and corresponding energy is between 2.8eV to 1.8 eV . therefore, the least band gap of the semiconductor to be used in LED , in order to have the emitted radiation to be in the visible region, should be 1.8 eV . Phosphorus doped gallium arsenide and gallium Phosphide are two such semiconductors.
Answered by | 04 Jun, 2014, 03:23: PM

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