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Optoelectronic junction devices (I) is considered one of the most asked concept.
7 Questions around this concept.
Given below are two statements: one is labeled as Assertion A and the other is labeled as Reason R
Assertion A: Photodiodes are preferably operated in reverse bias conditions for light intensity measurement.
Reason: The current in the forward bias is more than the current in the reverse bias for a junction diode. In the light of the above statements, choose the correct answer from the options given below:
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Photodiodes are used in forward bias usually for measuring the light intensity.
Reason R: For a p-n junction diode, at applied voltage
V the current in the forward bias is more than the current in the reverse bias for
is the threshold voltage and Vz is the breakdown voltage. In the light of the above statements, choose the correct answer from the options given below
A junction diode is connected to a 10 V source and resistor as shown in figure. The slope of load line on the characteristic curve of diode will be:
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Devices in which carriers are generated by photons are called optoelectronic devices.
The following are important examples of optoelectronic devices.
A photodiode is a p-n junction that consumes light energy to generate electric current. It is operated under reverse bias.
Reverse bias means that the p-side of the photodiode is connected to the negative terminal of the battery and the n-side is connected to the positive terminal of the battery.
It is also sometimes referred to as a photo-detector, photo-sensor, or light detector.
Suppose an optical photon of frequency is incident on a semiconductor, such that its energy is greater than the bandgap of the semiconductor (i.e.). This photon will excite an electron from the valence band to the conduction band leaving a vacancy or hole in the valence band. This increases the conductivity of the semiconductor.
And by measuring the change in the conductance (or resistance) of the semiconductor, one can measure the intensity of the optical signal. Thus photodiode can be used as a photodetector to detect optical signals.
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