Graphical analysis of the working principle of light-emitting diodes

Light-emitting diodes, commonly called LEDs, are one of the most common semiconductor devices. Most semiconductors are made of doped semiconductor materials (atoms and other substances). The conductor material of light-emitting diodes is usually gallium aluminum arsenide. In pure gallium aluminum arsenide, all atoms are perfectly bonded to their neighbors, leaving no free electrons to connect the current. In doped materials, the extra atoms change the electrical balance, either adding free electrons or creating holes through which electrons can pass. Both of these additional conditions make the material more conductive. Semiconductors with extra electrons are called N-type semiconductors. Because it carries extra negatively charged particles, free electrons flow from negatively charged areas to positively charged areas in N-type semiconductor materials. Semiconductors with extra "electron holes" are called P-type semiconductors. Because they carry positively charged particles, electrons can jump from one electron hole to another, flowing from negatively charged areas to positively charged areas.

 

Therefore, the electron holes themselves are shown to flow from positively charged areas to negatively charged areas. A diode is made of an N-type semiconductor material combined with a P-type semiconductor material, with electrons at each end. This arrangement allows current to flow in only one direction. When there is no voltage across the diode, electrons flow from the N-type semiconductor to the P-type semiconductor along the junction between the transition layers, forming a depletion zone. In the depletion zone, the semiconductor material will return to its original insulating state - all these "electron holes" will be filled, so there are no free electrons or electron vacuum areas and current cannot flow.

In order to get rid of the depletion zone, the N-type must move towards the P-type and the holes should move in the opposite direction. To achieve this, connect the N-type side of the diode to the negative pole of the current and the P-type to the positive pole of the current. At this time, the free electrons in the N-type material will be repelled by the negative electrons and attracted to the positive electrons. The electron holes in the P-type material will move in the other direction. When the voltage between the electrons is high enough, the electrons in the depletion zone will be in its electron holes and start to move freely again. The depletion zone disappears and the current flows through the diode.

 

If you try to make the current flow in the other direction, with the P-type end connected to the negative pole and the N-type end connected to the positive pole, the current will not flow. The negative electrons of the N-type material are attracted to the positive electrons. The positive electron holes of the P-type material are attracted to the negative electrons. Because the electron holes and electrons are moving in the wrong direction, no current flows through the junction and the loss area increases.

The reason why the diode emits light:

Light is a form of energy that can be released by atoms. It is made up of many tiny particle-like bundles that have energy and momentum but no mass. These particles are called photons, and are the most basic unit of light. Photons are released when electrons move. In atoms, electrons move in orbits around the atom. Electrons have different energies in different orbits. Generally speaking, electrons with greater energy move in orbits farther away from the nucleus. When an electron jumps from a lower orbit to a higher orbit, the energy level increases, and conversely, when it falls from a higher orbit to a lower orbit, the electron releases energy. The energy is released in the form of photons. Higher energy drops release higher energy photons, which are characterized by their high frequency.

A free electron falls from the P-type layer through the diode into an empty electron hole. This involves falling from the conduction band to a lower orbital, so the electron releases energy in the form of a photon. This happens in any diode, you just see the photons when the diode is made of certain materials. In the atoms of a standard silicon diode, for example, the atoms are arranged in such a way that when the electron falls over a relatively short distance, it is invisible to the human eye. As a result, the electrons are so low in frequency that they are invisible to the human eye.

In visible light emitting diodes, such as those used in digital clocks, the size of the gap determines the frequency of the photons, or in other words the color of the light. While all diodes emit light, most are not very efficient. In a normal diode, the semiconductor material itself absorbs a lot of the light energy and ends up. An LED is covered by a plastic bulb that concentrates the light in a specific direction.

 

Advantages of light emitting diodes:

The first is that LEDs have no filaments to burn out, so they last longer. In addition, the small plastic bulb of LEDs makes them more durable. They can also be more easily adapted to current electronic circuits. The light-emitting process of traditional incandescent lamps involves generating a lot of heat. This is a complete waste of energy. Unless you use the lamp as a heater, because most of the effective current does not directly produce visible light. LEDs generate very little heat, and relatively speaking, the more electricity that goes directly to light, the more it reduces the need for electricity.