Due to forward applied voltage pn junction device acts as a good conductor after overcoming the barrier potential.While, when reverse biasing is provided to a PN junction device then the width of the depletion region increases with supplied voltage. On applying a forward voltage to a PN junction device the depletion width decreases with the increase in supplied voltage.On the contrary, when a reverse voltage is applied to a device then the movement of only minority carriers generates small current, known as leakage current. The factor that generates a key difference between forward biasing and reverse biasing is that when a forward voltage is applied to a device then mainly the current flow due to the movement of majority charge carriers.
Key Differences between Forward Biasing and Reverse Biasing Thus, it is said that it behaves like an insulator. As in reverse biased condition, no any current flows due to the majority carriers through the device. This current is known as reverse saturation current. Due to this movement, a very small reverse leakage current flows through the device. However, the minority carriers in both the regions i.e., electrons in p side and holes in the n side experience repulsion from the battery terminals and move across the junction. Due to the increase in the width of the depletion region, the flow of current due to majority carriers somewhat gets restricted. Resultantly, this increases the depletion width. So, due to this, the majority carriers start moving away from the junction. Similarly, electrons in the n region attract towards the positive side of the battery. It is clear from the above figure that, the majority carriers present in p region i.e., holes attract towards the negative terminal of the battery. Let us have a look at the reverse biased arrangement of a PN junction diode: Definition of Reverse BiasingĪ PN junction device is in reverse biased condition when the p region is connected to the negative potential and n region is connected to the positive potential of the battery. After completely overcoming the barrier potential, the depletion region diminishes and a sharp flow of current is noticed because a large number of majority carriers now cross the junction region. With the increase in the applied forward voltage, the width of the depletion region decreases. The barrier potential is nothing but a region of neutral atoms that get generated due to temperature difference when no external voltage is provided to it. So, due to the repulsion from the externally provided supply, the majority carriers gain sufficient energy and overcome the barrier potential. Then the majority carriers from both sides, i.e., holes from p side and electrons from n side experience a repulsive force from the positive and negative terminal of the battery respectively.Īs we already know the Coulomb’s law of physics that like charges repel each other and unlike charges attract each other.
So, when forward biasing is provided to the device as shown above. Let us have a look at the representation of forward biasing applied to a PN junction diode: While in case of n-type semiconductor material electrons are the majority carriers and holes are the minority carriers. We already know that in a p-type semiconductor material, holes are present as majority carriers and electrons are present as the minority carriers. Zener diode, varactor diode, photodiode etc.Ī PN junction device is said to be in forward biased condition when the p region forms the connection with positive terminal and n region forms the connection with the negative terminal of the battery. P region is connected to negative and n region is connected to positive terminal of the battery.Īcts as conductor after overcoming potential barrierĪcts as insulator and almost negligible current flowsĭiodes that operates on specified biasing P region is connected to positive and n region is connected to negative side of the battery.
Content: Forward Vs Reverse BiasingĪlmost negligible current due to minority charge carriers. Let us now see the contents to be discussed under this article and then we will move further to understand other major differences between the two.