Hello friends In this article we will know what is Photo Diode? How does it work? What is photo diode package? And learn about many facts related to it.
photo-diode | Photo Diode
A photo-diode is a reverse-biased silicon or germanium pn junction in which reverse current increases when the junction is exposed to light. The opposite current in a photo-diode is proportional to the intensity of light falling on its pn junction. This means that the greater the intensity of light falling on the pn junction of the photo-diode, the greater will be the reverse current.
Principle of photo diode | Principal of Photo Diode
When a rectifier diode is reverse biased, it has a very small reverse leakage current. The same is true for the photo-diode. The reverse current is produced by thermally generated electron-hole pairs that are swept across the junction by the electric field created by the reverse voltage. In a rectifying diode, the reverse current increases with temperature due to the increase in the number of electron-hole pairs.
A photo-diode differs from a rectifier diode in that when its n junction is exposed to light, the reverse current increases with increase in light intensity and vice versa.
This is how it is explained. When light (photons) hits the “pn junction”, that energy is provided by the photons to the atoms in the junction, creating more free electrons (and more holes). These extra free Claytron reverses stream Will increase
As the intensity of the light incident at that PN junction increases, the reverse current also increases. In other words, as the intensity of the incident light increases, the resistance (photo-diode) curves.
Photo-diode package | Photo Diode package
Figure 33.13 shows a typical photo-diode package. It consists of an N junction mounted on an insulated substrate and sealed inside a metal case.
A glass window is fitted over the case to allow light to enter and strike the PN junction. The two leads extending from the case are labeled anode and cathode. The cathode is usually identified by the tab extending from the side of the case.
Figure 33.3 (ii) shows the schematic symbol of a photo diode. Inward arrows represent incoming light.
Read in Hindi: What is photo diode? , Photo Diode kya hota hai?