When p-n junction diode is forward biased then

Explanation

When a p-n junction diode is forward-biased, both the depletion region and barrier height are reduced. Here's an explanation of what happens: Depletion Region Reduction: In a p-n junction diode, there is a region called the depletion region or the space charge region. This region is essentially devoid of charge carriers (both electrons and holes) and acts as a barrier to the flow of electric current in the absence of an external voltage. When the diode is forward-biased, a positive voltage is applied to the p-side (anode), and a negative voltage to the n-side (cathode). This external voltage counteracts the built-in potential of the p-n junction, effectively reducing the width of the depletion region. As the width of the depletion region decreases, it becomes easier for charge carriers (electrons and holes) to move across the junction. This reduction in the depletion region allows for the flow of current in the forward direction. Barrier Height Reduction: The barrier height, also known as the built-in potential or barrier potential, is the energy difference between the conduction band of the n-type material and the valence band of the p-type material. It represents the energy barrier that charge carriers must overcome to move from one side of the diode to the other. When the diode is forward-biased, the external voltage applied reduces the effective height of this energy barrier. As a result, it becomes easier for electrons (from the n-side) to move into the p-side and combine with holes. This reduction in the barrier height facilitates the flow of current across the diode. In summary, forward-biasing a p-n junction diode reduces both the width of the depletion region and the barrier height, making it conducive to the flow of electric current in the forward direction. This is a fundamental characteristic of diode behavior in forward biasing.