What are Diodes?
A diode is a type of electronic component that features two-terminals, and they allow for current to be conducted in a single direction. With operations similar to that of a fluid valve, diodes may be used within electronic circuits in order to dictate the patch of electricity as it moves through a system. While simplistic in their functionality, a diode’s ability to maintain a single direction of current while impeding any reverse flow is beneficial for a number of electronic systems and applications. In this blog, we will discuss the common types of diodes and their functionalities, allowing you to understand their various uses in electronic systems.
The semiconductor diode is the most common type that is implemented within electronics currently, and electricity is conducted in a single direction based on a threshold voltage. When current is running through the electronic component in the standard direction, the diode is stated to be forward biased. Meanwhile, semiconductor diodes that are operated in the opposing, or resistant, direction are referred to as reverse biased. While the reverse direction is meant to impede the flow of current backwards, it is not entirely resistant. If the reverse voltage exceeds a specific range as dictated by the particular diode, current can run the opposite direction. When this occurs, it is referred to as a reverse breakdown voltage.
To know which direction that current may flow within a particular diode, there are often symbols and markings present. Generally, current will always run from the anode to the cathode side, as is seen in a p-n junction semiconductor diode. As the most common form of semiconductor diode, the p-n junction can be created through the doping of pentavalent or donor impurities on one side and trivalent or acceptor impurities on the other.
Generally speaking, the working principle of diodes are dependent upon how the n-type and p-type semiconductors interact with one another. As the n-type semiconductor will contain more free electronics as compared to the p-type semiconductor, fusing will begin when the diode is unbiased. When sufficient current is supplied for a forward biased configuration to surpass the potential barrier, majority charge carriers will begin to move forward along the current. As such, the diode can act as a short-circuited path.
If the source of current is connected to the negative terminal side, however, electrostatic attraction causes the holes of the p-type region to begin shifting. As a result, more negative ions would be present within the junction. At the same time, free electrons in the n-type region begin to move towards the positive side, and thus the depletion region of the diode grows larger. Through this process, the majority carriers move away from the junction, causing current to be impeded in its flow. While some reverse voltage may result from supplying current to the negative terminal side, only a small amount of current moves through the diode. If a large amount of current is forced through the diode in the reverse direction, the diode may be permanently damaged.
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