what is potential barrier and barrier width in a pn junction diode?

Current i think

The "Potential Barrier" is the junction between the N and P material that makes up the diode.

When the N and P-type semiconductor materials are first brought together some of the free electrons move across the junction to fill up the holes in the P-type material producing negative ions, but because the electrons have moved they leave behind positive ions on the negative N-side and the holes move across the junction in the opposite direction into the region where there are large numbers of free electrons. This movement of electrons and holes across the junction is known as diffusion. This process continues until the number of electrons which have crossed the junction have a large enough electrical charge to repel or prevent any more carriers from crossing the junction. Eventually a state of equilibrium (electrically neutral situation) will occur producing a "Potential Barrier" zone around the area of the junction as the donor atoms repel the holes and the acceptor atoms repel the electrons. Since no free charge carriers can rest in a position where there is a potential barrier it is therefore "depleted" of any free mobile carriers, and this area around the junction is now called the Depletion Layer.

The barrier width can be increased or decreased through the use of a "Bias Voltage". The larger the barrier width, the less current that flows, the smaller it is, the more flows.

For a good tutorial on junctions and diodes, take a look at

http://www.electronics-tutorials.ws/diode/diode_1....

in the pn diode the width of the barrier in forward bias is large under unbiased conditions. this is when the barrier potential will be equal to 0.7v. but when it is in forward bias the depletion region decreases and due to this the charge carriers flow from p side to n side. but when the width of the barrier decreases the potential should also decrease but it remains the same 0.7v. can anyone please tell me why i really want an answer .