|Radio and Electronics (DED Philippinen, 66 p.)|
|9. ACTIVE COMPONENTS -1- DIODES|
|9.2. THE PN-JUNCTION OR DIODE|
Up to this point, there was nothing connected to the PN-junction. Now we have to consider, what will happen at this junction if we connect a voltagesource to it.
If we connect the positive pole of the source to the N-type side and the negative pole to the P-type side, we can imagine the positive pole attracting the free electrons of the N-type side, and the negative pole attracting the holes of the P-type side, and so on both sides reducing the number of charge carriers there as shown in fig. 86 n.
This effect extents the depletion layer. Therefore the resistance of the junction is increased and therefore
IN REVERSE DIRECTION THERE WILL FLOW NO CURRENT.
If we connect the negative pole of the source to the N-type side and the positive pole to the P-type side, we can imagine the positive pole repelling the free holes of the P-type side in direction of the border, and the negative pole repelling the electrons of the P-type side in direction of the border.
So the charge carriers are invading the depletion layer it-will get conducting. Therefore the resistance of the junction is tremendously decreased and their depletion layer vanishes. IN FORWARD DIRECTION THERE WILL FLOW CURRENT.