Question

Explain the principle of operation of a photodiode.

Answer 1

The above problem can be explained on the basis of the working principle of the photodiode. The photodiode is the same as the normal diode but the input supply is given in the form of the light energy. The incident light contains various wavelengths of the light. The photodiode works on the principle of the photoelectric effect. The diode is the semiconductor device that allows the flow of current only in the single direction.

Complete step by step answer
The photodiode is made of the semiconducting material that requires only a small amount of the energy for the excitation of electrons in the semiconducting material. The excited electrons create a current in the material.
When the light falls on the surface of the photodiode then the energy of the photons transferred to charge carries of the diode. The charge carriers in the diode start moving due to excitation and it causes the flow of current in the diode. The diode allows the flow of current in one direction and restricts the flow of current in the other direction.
The minimum frequency of light that is necessary for starting the flow of current in the diode is called the cut off frequency. The cut off frequency varies according to the nature of the semiconductor material. The intensity of the current in the photodiode varies according to the frequency of the incident light.

Additional Information The diode consists of two regions in the semiconducting material. One is the P region and other is the N region. The P region contains the holes in excess and N region of the diode contains electrons in excess.

Note: The photodiode is very sensitive to incident light so the operation of the photodiode is controlled by the amount of the incident light. The photodiode is highly susceptible to the environment. If the surrounding environment is dusty then the operation of the photodiode gets disturbed.