Question

the band gap of the semiconductor used for the fabrication of visible LED 's must be at least 1.8eV. Why?

Answer 1

Only that energy gap will produce visible light.

Answer 2

Explanation:

• When the light enrgy is produced or formed needs to be in the Spectral limit ranges between 0.4 to 0.7 m.
• There are devices that are meant to produce this amount of energy. So that they can be seen in the form of light and certain semiconductors are are included in them.
• So, the band gap between the semiconductor should be a minimum of 1.8 eV.
• This is because a minimum of this band gap energy is able to produce a range of energy which can make it possible for the energy to reach the spectral limit and hence able to produce light.

To know more:

A p-n photodiode is made of a material with a band gap of 2 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly:-

a) 20 x 1014 Hz

b) 10 x 1014 Hz

c) 5 x 1014 Hz

d) 1 x 1014 Hz

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