PIN photodiode structure and equivalent circuit diagram

The PIN photodiode is named after a layer of intrinsic semiconductor (semiconductor) between the P-type layer and the N-type layer of the PN junction, forming a PIN structure, as shown in the following figure:

As shown in the above figure, in the device in the reverse bias state, the electric field E formed by the power supply at the PN junction is in the same direction as the built-in electric field Ei, and the depletion region is widened. When the light wave is injected, the carrier can be excited in a wide range. Since the electric field in the i region, the photogenerated carrier moves toward the electrode at a faster drift speed to form an external current.