InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Describe with suitable block diagrams, action of pn-junction diode under forward and reversebias conditions. Also draw I-V characteristics. |
Answer» Solution :PN Junction diode under forward bias  When the diode is forward biased as shown in the figure the depletion region width decreases and the barrier height is reduced. The electrons from n-sied cross the depletion region and reach p-side also HOLES cross the junction and reach the n-side. A CONCENTRATION gradient s developed at the junction boundary. Due to this the motion of charged carriers on either side gives RISE to current. The total diode forward current is sum of hole DIFFUSION current and CONVENTIONAL current due to electron diffusion. PN Junction diode under reverse bias  When the diode is reverse biased the depletion region width increases and the barrier height is increased. This supresses the flow of electrons from n-side to p-side and holes from p-side to n-side. Thus, diffusion current decreases. The conventional current is due to drift of the minority charge carriers which is of the order of micro amperes. The current under reverse bias is voltage independent up to a critical reverse bias voltage known as breakdown voltage. The I-V characteristics are as shown 
|
|