Forward biased
In the forward biased condition, p side (Anode) of the diode is connected with the positive terminal of the supply. And n side (cathode) is connected with the negative of the battery. Thereby causing the junction to be forward biased.
When forward biasing is applied. The holes in the p side experience a repulsive force from the positive terminal. Similarly, electrons experience a repulsion from the negative terminal of the supply provided. However, initially, the majority carriers from both the sides do not move across the junction due to barrier potential.But, as the barrier potential is exceeded, the majority charge carrier now shows movement across the junction. This movement of charge carriers after overcoming the barrier potential generates current.When the barrier is removed, the resistance becomes Zero and the current starts flowing in the device.
Reverse biased
In the reverse biased condition, p side (Anode) of the diode is connected with the negative terminal of the supply. And n side (cathode) is connected with the positive of the battery. Thereby causing the junction to be forward biased.
When the reverse supply is applied then the electrons in the n-side experiences an attraction from the positive supply of the voltage and holes in the p-side experiences an attraction from the negative supply.Due to this the majority carrier moves away from the junction and broaden the depletion layer.
Hence, the potential barrier increases and very small amount of current will flow.
