The world of engineering and technology keep advancing every day, but people tend not to know and understand the start, the basics and the genesis of this great adventure.
I keep on wandering, how do we come about all these electronics and garjets, I asked myself so many questions, is this part of the miracles and wonders of the old experienced by fore-fathers, are electronics made through magic and incantations, no, it should be by invoking spirits of dark power.

Amazingly, It possible to watch what is going on in every countries of the world on my television or on my laptop within the four corners of my room, you can actually watch Barcelona matches in Spain without being there, You can read my posts even though we've not met before, I can talk to my friend in France with a Mobile phone without facial contact, all these and other amazing inventions are made possible by a semiconductor.

FM Radio circuit arranged on a board for demonstration

What are semiconductor?

Semiconductors are solid chemical substance whose conductivity level is at the extreme ends of an insulator and a conductor, so they are neither a good conductor like copper nor an insulator like glass at room temperature. At a higher temperature, a semiconductor behaves like a conductor but at a lower temperature, it behave like an insulator. Also, semiconductor has it resistvity (10E-4 to 0.5 Ωm) in between conductors and insulators. Example of semiconductors include: Silicon, Germanium, carbon, and Selenium etc.

Why electronics are made by semiconductors

Some properties of semiconductors such as negative temperature co-efficient of resistance which means that the resistance of a semiconductor decrease with increase in temperature and the resistance increases with decrease in temperature, the resistivity of a semiconductor is more than that of a conductor but less than that of an insulator, also a semiconductor can undergo a process of doping in which a metallic impurity such as Arsenic and Gallium is added to an extremely pure semiconductor (intrinsic semiconductor) to form impurity or extrinsic semiconductor. Semiconductor devices have replaced vacuum tubes in old electronics and in most applications

video card with numerous semiconductor devices

When electric field is applied to an intrinsic semiconductor at room temperature, electron-hole pair is created, which means there will be free electrons and hole, conduction is made possible by these free electrons and holes under the influence of electric field, therefore, the sum of the current generated by holes and free electrons makes the total current inside a semiconductor. At room temperature the conduction capability of an intrinsic semiconductor is low. The semiconductor must be altered by significantly increasing its conducting properties before it can be used in electronic devices, to achieve this, some metallic impurities must be added to the pure semiconductor to for an extrinsic semiconductor.

P-type semiconductor crystal

When a semiconductor such as Germanium is doped, a p-type or n-type semiconductor is formed. Considering a germanium crystal, germanium atom has four valance electrons, n-type semiconductor is formed by adding a small amount of pentavalent ( an atom with five valence electrons) impurity such as arsenic to germanium crystal, numerous number of free electrons will be available in the crystal, the free electrons are highly mobile and engage in high conductivity of the semiconductor because the number of available free electrons out number the holes. P-type semiconductor is formed by adding a small amount of trivalent (atom with three valence electrons) impurity such as gallium to a germanium crystal, a numerous number of free holes will be generated in the crystal, these free holes are used for conduction in p-typed semiconductors.

n-type semiconductor crystal

Semiconductors are easily manipulated or can be easily controlled by adding impurities. The amount of impurities to be added to a pure semiconductor depends on function and the type of semiconductor devices to be fabricated.

Lighting, Dj, Disco, Spots, Led for Blue projection

The wonder works of a semiconductor devices

Amazing behavior of the above properties of semiconductors, make it suitable for fabricating electronic devices like transistors, diodes, resistors, capacitors, operational amplifiers integrated circuits(ICs) etc. These electronic devices are the contents or components of any electronics you can think about, they are very cheep, readily available in the market, easy to handle, not difficult to use, not bulky, and they are very functional.
Try opening your transistor radio, all the components in the transistor radio are semiconductor devices.
The families of transistor includes npn transistors, pnp transistors, Feild effect transistors (FET), Bi-polar junction transistor, metal oxide semiconductor field effect transistors (MOSFET) etc.

some semiconductor devices

Functions of these semiconductor devices in electronics

Considering a transistor radio, let look at the functions of the fore mentioned electronic devices in a transistor radio circuit.

Resistors: resistors are two terminal electronic device, used to limit the flow of currents in a circuit. let say current of 2 amperes is needed in a particular section of the radio circuit but 4 amperes of current was supplied from the power supply, a resistor is attached to the end of the 4 ampere supply to reduce to amount of current needed to 2 amperes.

Capacitors: capacitor is also a two terminal electronic device, used to store charges, to ensure continuous flow of current in a circuit. This keeps you radio working without sudden going off and on.

Transistor: transistor is used to control electrons thereby controlling the flow of electricity in a circuit. They function like a water faucet, not only to start and stop the flow of a current, but also to control the amount of the current flow. They are used for mostly for amplification such as sound amplification in radio speaker and also for switching from a radio frequency to another.

Integrated circuit (ICs) are programmable electronic devices, it accomplishes set of instruction store in it.

Diode allows the flow of electrons or current in one direction, it function to ensure that current from the battery of your transistor radio only flows to all parts of the the radio circuits and never return back to the battery.

semiconductor devices

The topic of discussion can not be exhausted in this episode, I will continue in the next episode. Hope you have added some knowledge from this post.

Thanks for your time.

References
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