The working principle of LED (Light Emitting Diode) is based on a phenomenon known as electroluminescence. Electroluminescence is the process by which light is emitted from a material when an electric current is passed through it.
LEDs are made from a semiconductor material, typically a compound called gallium arsenide (GaAs) or gallium phosphide (GaP). These materials are doped with impurities to create a p-n junction, which is the key component of an LED.
The p-n junction is formed by bringing together two types of semiconductor material: p-type and n-type. The p-type material contains an excess of positively charged carriers, known as holes, while the n-type material contains an excess of negatively charged carriers, known as electrons. When the two materials are joined together, the electrons and holes near the junction region combine and release energy in the form of photons (light).
To achieve this, a forward bias voltage is applied to the p-n junction by connecting the positive terminal of a power source to the p-type region and the negative terminal to the n-type region. When current flows through the p-n junction, electrons from the n-type region recombine with the holes from the p-type region, resulting in the release of energy in the form of light.
The specific wavelength or color of the emitted light depends on the energy bandgap of the semiconductor material. Different materials and dopants can be used to produce LEDs that emit light in various colors such as red, green, blue, and other colors.
LEDs have several advantages over traditional incandescent or fluorescent lights, including lower power consumption, longer lifespan, and faster switching speeds. These characteristics make LEDs widely used in various applications, including lighting, displays, indicators, and many electronic devices.
