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प्रश्न
Write the important considerations which are to be taken into account while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED). What should be the order of the band gap of an LED, if it is required to emit light in the visible range? Draw a circuit diagram and explain its action.
उत्तर
For the formation of LED direct bandgap semiconductors like GaAs, CdS, etc should be used which emits light. The p-n junction should be operated in forwarding bias. Most of the Light is produced in p-area of the device so while fabricating LED this area is kept close to the surface of the diode so that the minimum amount of energy is absorbed. One can use different materials for producing different colored Lights. The semiconductor used for the fabrication of visible LEDs must at least have a bandgap of 1.8 eV. The order of the band gap if it is required to emit light in the visible range is about 3 eV to 1.8 eV.
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संबंधित प्रश्न
If a small voltage is applied to a p-n junction diode, how will the barrier potential be affected when it is (i) forward biased
The width of depletion region of p-n junction diode is _______.
(A) 0.5 nm to 1 nm
(B) 5 nm to 10 nm
(C) 50 nm to 500 nm
(D) 500 nm to 1000 nm
State its any ‘two’ uses of photodiode.
Write briefly the important processes that occur during the formation of p−n junction. With the help of necessary diagrams, explain the term 'barrier potential'.
How is a photodiode fabricated?
Briefly explain its working. Draw its V - I characteristics for two different intensities of illumination ?
Draw the circuit diagram of an illuminated photodiode in reverse bias. How is photodiode used to measure light intensity?
Draw the circuit arrangement for studying the V-I characteristics of a p-n junction diode in reverse bias. Plot the V-I characteristics in this case.
Choose the correct answer from given options
The wavelength and intensity of light emitted by a LED depend upon
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. lt can detect a signal of wavelength ______.
