What is Forward Bias?

A diode is a small electronic element that lets the current passing through the component flow only in one direction but not the other. Biasing is carried out in a diode to regulate the direction of the current in the diode. Biasing a diode is done in two different ways. 

They are forward bias and reverse bias. On setting up a bias in the diode, the path of the current alters in the opposite direction. We will learn what is forward bias, its characteristics and the significance of forward bias.

Biasing a P-N junction of the diode

Biasing is the process of shifting the current to only one direction so that the flow of current is resisted or inhibited in the opposite direction. 

• Biasing occurs in a P-N junction in semiconductors such as diodes. 
• There are two types of semiconductors in the P-N junction—the p-type and n-type within the same crystal.
• The p-type is the anode side that contains holes in maximum number.
• The positive particles, the holes, move from p to n but not from n to p.
• The n-type is the cathode that has electrons in a maximum number.
• The negative electrons transport from n to p, but it is not from p to n.
• Forward bias makes the current flow easy and at a maximum level.
• Reverse bias makes the current flow slower.

What is forward bias?

Forward bias in a P-N junction diode allows the continuous flow of current in one particular direction without any disturbance or interference.

• Forward bias meaning is that the current flows in the forward direction due to the voltage applied in the forward direction.
• In forward bias, the p-type(anode) of the semiconductor is connected to the positive end, and the n-type(cathode) is connected to the negative end of the battery.
• Thus, the voltage at the anode is higher than the voltage at the cathode side.
• It allows the current to flow from the p-type(anode) to the n-type(cathode), considering it as the forward direction.

What happens when a diode is forward biased?

Forward bias lets the current flow in the forward direction in a diode. 

• To make the current flow in the forward direction, the p-type is connected to the positive end having a higher voltage, and the n-type to the negative end has a lower voltage. 
• On connecting the positive end to the p-type, the positive impurity holes present there are pushed towards the junction due to repulsion of the same positive charges.
• On connecting the positive end to the p-type, the positive impurity holes present are pushed towards the junction due to the repulsion of the positive charges.
• Once all these holes and electrons are flushed towards the junction, they form a depletion region where the electrons and holes are present in mass.
• After some time, the depletion region vanishes when the voltage is high enough.
• The electrons and holes that overcame the depletion region at the P-N junction allow the free electrons in the current to pass freely through the semiconductor.

What happens when a diode is reverse biased?

• In reverse bias, the p-type anode connects to the negative terminal, and the n-type cathode connects with the positive terminal.
• Thus, when the diode is in reverse bias, the electrons and holes are pushed away from the junction, widening the depletion region.
• Under high voltage, the depletion regions vanish due to the Zener breakdown or Avalanche effect. 

• The current in a reverse-bias diode reverses in direction.
• In a reverse-bias diode, the voltage at the cathode is comparatively higher and builds up the potential barrier.
• The depletion region is thicker, and the circuit has a high resistance.
• A reverse-biased material will be the same as an insulator.

Forward bias importance and characteristics

The importance and characteristics of forward bias are given below.

• Forward bias lets the current flow in only one direction, that is the forward direction, from the positive terminal to the negative.
• The voltage is higher at the anode than the voltage of the cathode.
• It decreases the potential barrier strength in the circuit.
• Forward bias has a very thin depletion layer compared to reverse bias.
• It minimises the circuit resistance, increasing the current flow.
• It is useful in converting AC( alternating current) to DC (direct current).
• The circuit becomes an efficient conductor when it is forward biased.

Conclusion

We have now learnt what forward bias is, its definition and its characteristics. In forward bias, the diode makes the current flow in the forward direction. The current flows from p-type to n-type due to forward biasing in a P-N junction diode. The forward bias is crucial where the current flow has to be consistent and effortless. The resistance of a forward-biased material is very low. These characteristics make a forward-biased material a perfect conductor due to the easy flow of electrons and holes in the diode material.