How does a PN junction photodiode operate?

Question

What will be an ideal response?

Answer 1

A PN junction photodiode operates on the same principles as a photovoltaic cell except that it is used to control current flow, not generate it. A reverse-bias voltage is applied across the photodiode, forming a wide depletion region. When light energy strikes the photodiode, it enters the depletion region, creating free electrons. The electrons are drawn toward the positive side of the bias source. A small current flows through the photodiode in the reverse direction. As the light energy increases, more free electrons are generated, creating more current flow.