An LED (Light Emitting Diode) differs from a standard diode primarily in its ability to emit light when forward biased. Both LEDs and diodes are semiconductor devices with a PN junction, but LEDs are specifically designed to convert electrical energy into visible light. When current flows through an LED in the forward direction, electrons recombine with holes in the semiconductor material, releasing energy in the form of photons. This process generates the characteristic light emission of LEDs, which can produce various colors depending on the semiconductor material used.
LED diode is not a standard term; typically, LEDs are referred to simply as LEDs. However, the term might be used informally to emphasize that LEDs are a type of diode with the additional capability of emitting light. In essence, an LED is a diode but with specialized functionality to emit light, distinguishing it from conventional diodes that do not emit light when forward biased.
The main difference between an LED and a normal PN junction diode lies in their intended function and design. A normal PN junction diode, also known as a semiconductor diode, allows current to flow in one direction (forward bias) and blocks it in the opposite direction (reverse bias). Its primary function is to control the direction of current flow in electronic circuits and to rectify AC voltage to DC. In contrast, an LED shares the same basic structure of a PN junction diode but is optimized to emit light when forward biased, making it suitable for applications in lighting, displays, indicators, and optoelectronic devices.
Not every diode is an LED. Diodes encompass a broad category of semiconductor devices with a PN junction that exhibit rectification properties. They include standard silicon diodes, Schottky diodes, Zener diodes, and others, each designed for specific functions such as rectification, voltage regulation, or switching. LEDs are a specialized subset of diodes designed specifically for light emission. While both LEDs and standard diodes share the basic structure of a PN junction, LEDs are distinguished by their ability to emit light when forward biased due to the energy released during electron-hole recombination.
You can use an LED as a diode for basic rectification purposes in circuits where a standard diode is typically used. When forward biased, an LED behaves like a regular diode, allowing current to flow in one direction and blocking it in the reverse direction. However, LEDs have different electrical characteristics compared to standard diodes, including a slightly higher forward voltage drop and specific current ratings. While LEDs can function as diodes in many applications, it’s important to consider their specifications, particularly their maximum current and voltage ratings, to ensure reliable operation and longevity in the circuit.