Semiconductors and electronic circuits have been causing a leap that can not be ignored. Thanks to semiconductors, the author of this article was able to write it, and you are able to read it. There isn’t anyone on earth who has never used semiconductors before in some way or another.
In this article, we will learn about semiconductors and how they work. We will also mention some devices which resulted in creating the innovations we use today, such as radio, television, car, air conditioner, computers, mobile phones, and all modern communication devices and many household appliances.
Table of Contents
Materials are classified into three classes according to their ability to transfer electricity. Firstly, we have conductors, which are materials that can easily connect electricity. They have a large number of free electrons due to the weakness of the attracting force between the nucleus and valence electrons (i.e. electrons in the last orbit of the atoms). Valence electrons are transformed into free electrons causing the flow of electrical current.
We also have insulators, which are materials that do not have free electrons. These don’t allow the electric current to flow because of the strong attracting force between the nucleus and valence electrons.The third type of materials has medium ability to conduct electricity. These materials are called semiconductors such as silicon and germanium.
The ability of semiconductors to conduct electricity is affected by various factors such as temperature, impurities, incident light, and voltage. By changing these factors, semiconductors are either completely insulators or conductors. This property is what makes semiconductors that important.
How It Works
It is known that the conductivity of any material is based primarily on the movement of electrons, as electrons carry the current through the material. Moreover, it is known that the nucleus has a positive charge and, on the other hand, the electrons have a negative charge. Thus, there is a force of attraction between the nucleus and electrons. Therefore, electrons must escape from this attraction to allow the current to pass through the material.
In solid materials, some electrons exist in two bands: conduction bands and valence band. The electrons that exist in conduction band move easily within the material without leaving their crystals. The electrons in the valence band are confined and do not conduct the current, as they are closer to the nucleus than free electrons.
On one hand, in conductors, there is no separation between the valence band and the conduction band. Electrons in the two bands are intertwined so that the valence electrons move easily between the two bands. On the other hand, the insulating materials have a large separation between the two bands.
Last but not least, the separation between the two bands in semiconductors is average. Thus, valence electrons can jump to the conduction band if they acquire an amount of the energy that helps them pass the separator, giving the semiconductor the ability to deliver electricity.
Application of Semiconductors
Let’s check some of the innovations that depend on the semiconductors.
It is one of the simplest semiconductor devices. It is made up of a piece of silicon, half of which set with impurities of N-Type, and the other half set with impurities of P-type. There are many important applications for diodes in electric and digital circuits. The main advantage of the diode is to allow the current to pass in one direction and prevent it in other direction.
Half-Wave Rectifier: It is used to produce a direct current (DC). However, it has intermittent intensity at half a cycle, and it disappears at the other half.
Full-Wave Rectifier: It converts alternating current (AC) to DC. It is used in many battery-operated applications and in the solar cell, as it can only generate continuous currents.
Varactor diode: This device is used to tune the frequency of the resonance of an electric circuit. Also, it is used to produce a phase-locked loop, which is a control system that generates an output signal whose phase is related to the phase of an input signal. It is used in radio, television, cell phones, and various transmitters.
Photodiode: In the photodiode, silicon absorbs the energy of the photons of the incident light to create additional pairs of electrons and gaps, causing a significant change in current intensity. It is used in solar cells, light sensor in smartphones, digital cameras, street lighting lamps, as well as shopping malls doors.
LED: LED is a light emitting diode characterized by rapid response, small size, and longer life expectancy. It spreads widely and is used as an alternative to fluorescent lamps and tungsten.
We have mentioned the most important and famous uses of the diode in our daily lives, and there are still many and many other applications around us for this wonderful innovation.
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