Q1Analog Circuits
Question
2 marks
How depletion layer is formed in diode?
Answer
The depletion layer is formed by the diffusion and recombination of holes and electrons across the PN junction, leaving immobile ions.
When a PN junction is formed, the high concentration of holes in the P-type region and electrons in the N-type region causes them to diffuse across the junction.
As electrons move into the P-region they recombine with holes, and vice versa. This leaves behind uncovered, immobile positive ions in the N-region and negative ions in the P-region. This region stripped of mobile charge carriers is called the depletion layer, which creates an electric field that eventually stops further diffusion.