A rectifier diode is a semiconductor device that converts alternating current (AC) to direct current (DC). A rectifier diode contains a PN junction and has two terminals: anode (positive) and cathode (negative). The most important characteristic of a rectifier diode is its unidirectional conductivity. In a circuit, the current can only flow into the anode and out of the cathode. There are many types of rectifier diodes, and they come in a variety of packaging forms.
Rectifier diodes can be divided into various types such as standard rectifier diodes, switching diodes, fast recovery diodes, and Schottky diodes. Different types of rectifier diodes have significant differences in parameters and performance, and their application fields are also different. However, their basic working principle and related parameter definitions are entirely the same.
The N-type and P-type materials of a rectifier diode are chemically bonded using special manufacturing techniques to form a PN junction. Because this PN junction has two terminals that can be considered electrodes, it is called a diode. When an external DC power voltage is applied across its terminals to any electronic device, biasing occurs.
Unbiased Rectifier Diode
When no voltage is applied to the rectifier diode, it is referred to as an unbiased rectifier diode.
The N side will have mostly electrons and fewer holes due to thermal excitation, while the P side will have mostly hole charge carriers and fewer electrons. In this process, free electrons from the N side will diffuse to the P side and recombine with the existing holes, resulting in fixed positive ions on the N side and fixed negative ions on the P side.
Near the edge of the junction on the N-type side, there are immobile ions, and similarly, there are fixed ions near the edge of the junction on the P-type side. Therefore, a significant number of positive ions and negative ions accumulate at the junction, forming a region called the depletion region. In this region, an electrostatic field, known as the barrier potential, is formed across the PN junction, preventing further migration of holes and electrons through the junction.
Forward Biased Rectifier Diode
In a PN junction diode, when the positive terminal of a voltage source is connected to the P-type side and the negative terminal is connected to the N-type side, the diode is in a forward-biased state.
Electrons are repelled by the negative terminal of the DC voltage source and drift toward the positive terminal. Therefore, under the influence of the applied voltage, this electron drift causes current to flow through the semiconductor, which is referred to as "drift current." Since the majority carriers are electrons, the current in the N-type material is electron current.
Since holes are the majority carriers in the P-type material, they are repelled by the positive terminal of the DC voltage source and move across the junction to the negative terminal. Thus, the current in the P-type material is hole current. Therefore, the total current produced by the majority carriers results in forward current. The conventional current direction flows from the positive terminal of the battery to the negative terminal, opposite to the direction of electron flow.
In summary, a rectifier diode is a fundamental component for power supplies, enabling the conversion from AC to DC and ensuring reliable operation of electronic devices. Understanding its function and choosing the appropriate type of rectifier diode is crucial for designing efficient and effective power systems. As one of the professional rectifier diode manufacturers, SEMIPOWER is committed to providing customers with high-performance rectifier diodes. Choosing SEMIPOWER's rectifier diodes can ensure your electronic devices operate reliably and efficiently.
