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Learn about the construction, working principle, and advantages of photodiodes. Explore their applications in event counting, optical fiber communication, photodetectors, solar panels, optocouplers, cameras, and light intensity meters.
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Kalwan Education Society’s Arts, Commerce and Science College, Kalwan (Manur) Topic: Photodiode Presented by, Miss. A. R. Kothawade
Content: 1.Introduction: 2.Construction and working: 3.I-V characteristics: 4.Advantages and Disadvantages: 5.Application: 6. Comparison of LED and Photodiode
Introduction A Photodiode is p-n junction semiconductor diode which is always operated in the reverse biased condition. Symbol of Photodiode: anode cathode
Construction and working: 1. The light is always focused through a glass lens on the junction of the photodiode. 2. As the photodiode is reverse biased, the depletion region is quit wide, penetrated on both side of the junction. 3.The photons incident on the depletion region will impart their energy to ions present there and generate electron hole pairs.
4. Numbers of electron hole pairs will be dependent on the intensity of light(number of photons).These electrons and holes will be attracted towards the positive and negative terminals respectively of the external source, to constitute the photo current. 5. With increase in the light intensity, more number of electron hole pairs are generated and the photocurrent increases. Thus the photocurrent is proportional to the light intensity.
Advantages 1.It has better frequency response. 2.It has lower noise. 3.High sensitivity. 4.High speed of operation as compared to the LDR.
Disadvantages 1.Dark current increases with temp. 2. Poor temperature stability. 3. It needs offset voltages. 4. It has the small active area. 5. External bias voltage is essential for operation. 6.Amplitification is required as the output current of small magnitude.
Application: 1.The most popular application is in event counting. 2.In optical fiber communication system. 3. In photodetector circuit. 4.In solar panel. 5.In optocoupler. 6.In cameras for sensing the light intensity. 7.In light intensity meters.
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