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When a p-type semiconductor is fused to an n-type semiconductor, a potential barrier voltage across the diode junction is formed.
The effect described in the previous tutorial is achieved without applying any external voltage to the actual P-N junction, resulting in the junction being in an equilibrium state.
However, if we make electrical connections at the ends of both the N-type and P-type materials and then connect them to a battery source, we now have an additional energy source to overcome the potential barrier.
The PN junction’s behaviour in relation to the potential barrier’s width results in an asymmetrical conducting two terminal device known as the PN Junction Diode.
What is P-N Junction Diode?
It has two sides, one positive (p) and one negative (n). If you’re reading this lesson on a computer or laptop that’s plugged into an outlet, you’re probably using a diode right now. If you keep reading, you’ll discover where you’re most likely to find this diode.
But for now, let’s look at the components of a p-n junction diode. It’s a really simple little thing. The majority of them are made of silicon, which allows the diode to operate at higher temperatures, which is important for preventing your electronics from overheating.
A different impurity is added to each side of a silicon semiconductor to change the number of extra holes or electrons present to create a p-n junction diode. There are an equal number of holes and electrons in a pure silicon semiconductor. If there are more holes than electrons on one side, it is called the p-side. If there are more electrons than holes, the n-side is formed.
However, just because a material has a positive and negative side does not imply that it is electrically charged. Despite the addition of impurities, the material remains electrically neutral. The added impurities simply leave holes or add more free electrons.
Flow of Current in P-N Junction Diode
When the voltage is raised, electrons move from the n-side of the junction to the p-side. As the voltage increases, holes migrate from the p-side to the n-side of the junction in a similar manner. As a result, a concentration gradient exists between both terminals.
The development of the concentration gradient will cause charge carriers to move from higher concentration regions to lower concentration regions. The movement of charge carriers inside the p-n junction causes current flow in the circuit.
What is a P-N Junction Semiconductor Diode?
A p-n junction diode is a two-terminal or two-electrode semiconductor device that allows current to flow in only one direction while blocking current flow in the opposite or reverse direction. If the diode is forward biased, electric current can flow. If, on the other hand, the diode is reverse biassed, it blocks the flow of electric current. The p-n junction semiconductor diode is also known as the p-n junction semiconductor device.
Application of P-N Junction Diode
When the p-n junction diode is reverse-biased, it can be used as a photodiode because it is light sensitive.
It has the capability of being used as a solar cell.
When forward-biased, the diode can be used in LED lighting applications.
It is used as a rectifier in many electric circuits, and as a voltage-controlled oscillator in varactors.
P-N Junction Formula
The p-n junction formula, which is based on the electric field’s built-in potential difference, is as follows:
E0 = VTln [ (ND – NA )/ ni² ]
Where, E0 is the zero-bias junction voltage. The concentrations of impurities are denoted by the letters ND and NA, The intrinsic concentration is denoted by the symbol ni.
Advantages of P-N Junction Diode
The p-n junction diode is the most basic type of semiconductor device. Diodes, on the other hand, play an important role in many electronic devices.
To convert alternating current (AC) to direct current (DC), a p-n junction diode can be used (DC). These diodes are found in power supplies.
If the diode is forward biased, current can flow. However, if it is reverse biased, it prevents current flow. In other words, when a p-n junction diode is forward biased, it becomes on, whereas when it is reverse biased, it becomes off (I.e. it acts as a switch). As a result, in digital logic circuits, the p-n junction diode serves as an electronic switch.
Conclusion
When a p-type semiconductor is fused to an n-type semiconductor, a potential barrier voltage across the diode junction is formed. The effect described in the previous tutorial is achieved without applying any external voltage to the actual P-N junction, resulting in the junction being in an equilibrium state. The P-N junction’s behaviour in relation to the potential barrier’s width results in an asymmetrical conducting two terminal device known as the P-N Junction Diode. A different impurity is added to each side of a silicon semiconductor to change the number of extra holes or electrons present to create a p-n junction diode. The movement of charge carriers inside the p-n junction causes current flow in the circuit. A p-n junction diode is a two-terminal or two-electrode semiconductor device that allows current to flow in only one direction while blocking current flow in the opposite or reverse direction.
